20,000

20,000 (twenty thousand) is the natural number that comes after 19,999 and before 20,001.

← 19999 20000 20001 →
List of numbers — Integers ← 0 [[{{#expr:{{{1}}}*{{{factor}}}*1000}} (number)|{{#ifeq:{{{1}}}|10|→|{{#expr:{{{1}}}*{{{factor}}}}}k}}]] [[{{#expr:{{{1}}}*{{{factor}}}*1000}} (number)|{{#ifeq:{{{1}}}|10|→|{{#expr:{{{1}}}*{{{factor}}}}}k}}]] [[{{#expr:{{{1}}}*{{{factor}}}*1000}} (number)|{{#ifeq:{{{1}}}|10|→|{{#expr:{{{1}}}*{{{factor}}}}}k}}]] [[{{#expr:{{{1}}}*{{{factor}}}*1000}} (number)|{{#ifeq:{{{1}}}|10|→|{{#expr:{{{1}}}*{{{factor}}}}}k}}]] [[{{#expr:{{{1}}}*{{{factor}}}*1000}} (number)|{{#ifeq:{{{1}}}|10|→|{{#expr:{{{1}}}*{{{factor}}}}}k}}]] [[{{#expr:{{{1}}}*{{{factor}}}*1000}} (number)|{{#ifeq:{{{1}}}|10|→|{{#expr:{{{1}}}*{{{factor}}}}}k}}]] [[{{#expr:{{{1}}}*{{{factor}}}*1000}} (number)|{{#ifeq:{{{1}}}|10|→|{{#expr:{{{1}}}*{{{factor}}}}}k}}]] [[{{#expr:{{{1}}}*{{{factor}}}*1000}} (number)|{{#ifeq:{{{1}}}|10|→|{{#expr:{{{1}}}*{{{factor}}}}}k}}]] [[{{#expr:{{{1}}}*{{{factor}}}*1000}} (number)|{{#ifeq:{{{1}}}|10|→|{{#expr:{{{1}}}*{{{factor}}}}}k}}]] [[{{#expr:{{{1}}}*{{{factor}}}*1000}} (number)|{{#ifeq:{{{1}}}|10|→|{{#expr:{{{1}}}*{{{factor}}}}}k}}]]
Cardinal	twenty thousand
Ordinal	20000th (twenty thousandth)
Factorization	2^5 × 5^4
Greek numeral	${\displaystyle {\stackrel {\beta }{\mathrm {M} }}}$
Roman numeral	XX
Binary	1001110001000002
Ternary	10001022023
Octal	470408
Duodecimal	B6A812
Hexadecimal	4E2016

20,000 is a round number, and is also in the title of Jules Verne's novel Twenty Thousand Leagues Under the Sea.

Selected numbers in the range 20001–29999

20001 to 20999

• 20081 – Motorola 68K instruction for no operation (NOP)
• 20100 – sum of the first 200 natural numbers (hence a triangular number)
• 20160 – highly composite number;[1] the smallest order belonging to two non-isomorphic simple groups: the alternating group A₈ and the Chevalley group A₂(4)
• 20161 – the largest integer that cannot be expressed as a sum of two abundant numbers
• 20230 – pentagonal pyramidal number[2]
• 20412 – Leyland number:[3] 9³ + 3⁹
• 20540 – square pyramidal number[4]
• 20569 – tetranacci number[5]
• 20593 – unique prime in base 12
• 20736 – 12⁴, 10000₁₂, palindromic in base 15 (6226₁₅)
• 20903 – first prime of form 120k + 23 that is not a full reptend prime

21000 to 21999

• 21025 – 145², palindromic in base 12 (10201₁₂)
• 21147 – Bell number[6]
• 21181 – the least of five remaining Seventeen or Bust numbers in the Sierpiński problem
• 21856 – octahedral number[7]
• 21952 – 28³
• 21978 – reverses when multiplied by 4: 4 × 21978 = 87912

22000 to 22999

• 22050 – pentagonal pyramidal number[2]
• 22140 – square pyramidal number[4]
• 22222 – repdigit, Kaprekar number:[8] 22222² = 493817284, 4938 + 17284 = 22222
• 22447 – cuban prime[9]
• 22527 – Woodall number: 11 × 2¹¹ − 1[10]
• 22621 – repunit prime in base 12
• 22699 – one of five remaining Seventeen or Bust numbers in the Sierpiński problem

23000 to 23999

• 23401 – Leyland number:[3] 6⁵ + 5⁶
• 23409 – sum of the cubes of the first 17 positive integers
• 23497 – cuban prime[9]
• 23821 – square pyramidal number[4]
• 23969 – octahedral number[7]
• 23976 – pentagonal pyramidal number[2]

24000 to 24999

• 24211 – Zeisel number[11]
• 24336 – 156², palindromic in base 5: 1234321₅
• 24389 – 29³
• 24571 – cuban prime[9]
• 24601 – Jean Valjean's prisoner number in Les Misérables
• 24631 – Wedderburn-Etherington number[12]
• 24649 – 157², palindromic in base 12: 12321₁₂
• 24737 – one of five remaining Seventeen or Bust numbers in the Sierpinski problem

25000 to 25999

• 25011 – the first composite number that in base 10 remains composite after any insertion of a digit
• 25085 – Zeisel number[11]
• 25117 – cuban prime[9]
• 25200 – highly composite number[1]
• 25205 – largest number whose factorial is less than 10¹⁰⁰⁰⁰⁰
• 25585 – square pyramidal number[4]

26000 to 26999

• 26214 – octahedral number[7]
• 26227 – cuban prime[9]
• 26861 – smallest number for which there are more primes of the form 4k + 1 than of the form 4k + 3 up to the number, against Chebyshev's bias
• 26896 – 164², palindromic in base 9: 40804₉

27000 to 27999

• 27000 – 30³
• 27434 – square pyramidal number[4]
• 27559 – Zeisel number[11]
• 27648 – 1¹ × 2² × 3³ × 4⁴
• 27720 – highly composite number;[1] smallest number divisible by the numbers 1 to 12 (there is no smaller number divisible by the numbers 1 to 11)
• 27846 – harmonic divisor number[13]

28000 to 28999

• 28158 – pentagonal pyramidal number[2]
• 28374 – smallest integer to start a run of six consecutive integers with the same number of divisors
• 28393 – unique prime in base 13
• 28561 – 13⁴, 119² + 120², number that is simultaneously a square number and a centered square number, palindromic in base 12: 14641₁₂
• 28595 – octahedral number[7]
• 28657 – Fibonacci number,[14] Markov number[15]
• 28900 – 170², palindromic in base 13: 10201₁₃

29000 to 29999

• 29241 – sum of the cubes of the first 18 positive integers
• 29341 – Carmichael number[16]
• 29370 – square pyramidal number[4]
• 29791 – 31³

References

1. "Sloane's A002182 : Highly composite numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-15.
2. "Sloane's A002411 : Pentagonal pyramidal numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-15.
3. "Sloane's A076980 : Leyland numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-15.
4. "Sloane's A000330 : Square pyramidal numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-15.
5. "Sloane's A000078 : Tetranacci numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-15.
6. "Sloane's A000110 : Bell or exponential numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-15.
7. "Sloane's A005900 : Octahedral numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-15.
8. "Sloane's A006886 : Kaprekar numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-15.
9. "Sloane's A002407 : Cuban primes". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-15.
10. "Sloane's A003261 : Woodall numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-15.
11. "Sloane's A051015 : Zeisel numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-15.
12. "Sloane's A001190 : Wedderburn-Etherington numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-15.
13. "Sloane's A001599 : Harmonic or Ore numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-15.
14. "Sloane's A000045 : Fibonacci numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-15.
15. "Sloane's A002559 : Markoff (or Markov) numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-15.
16. "Sloane's A002997 : Carmichael numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-15.