← 39999 40000 40001 →
List of numbers Integers ← 0 10k 20k 30k 40k 50k 60k 70k 80k 90k →
Cardinal	forty thousand
Ordinal	40000th (forty thousandth)
Factorization	26 × 54
Divisors	35 total
Greek numeral
Roman numeral	XL
Binary	10011100010000002
Ternary	20002121113
Senary	5051046
Octal	1161008
Duodecimal	1B19412
Hexadecimal	9C4016

40,000 (forty thousand) is the natural number that comes after 39,999 and before 40,001. It is the square of 200.

• 40320 = smallest factorial (8!) that is not a highly composite number
• 40425 = square pyramidal number
• 40585 = largest factorion^[1]
• 40678 = pentagonal pyramidal number
• 40755 = the smallest number >1 to be a Triangular number, Pentagonal number, and a Hexagonal number.^[2] Additionally, it's a 390-gonal, 4077-gonal, and 13586-gonal number.^[3][4][5]
• 40804 = palindromic square

• 41041 = Carmichael number^[6]
• 41472 = 3-smooth number, number of reduced trees with 24 nodes^[7]
• 41586 = Large Schröder number
• 41616 = triangular square number^[8]
• 41835 = Motzkin number^[9]
• 41841 = 1/41841 = 0.0000239 is a repeating decimal with period 7

• 42680 = octahedral number^[10]
• 42875 = 35³
• 42925 = square pyramidal number

• 43261 = Markov number^[11]
• 43380 = number of nets of a dodecahedron
• 43390 = number of primes .^[12]
• 43560 = pentagonal pyramidal number
• 43691 = Wagstaff prime^[13]
• 43777 = smallest member of a prime sextuplet

• 44044 = palindrome of 79 after 6 iterations of the "reverse and add" iterative process^[14]
• 44100 = sum of the cubes of the first 20 positive integers 44,100 Hz is a common sampling frequency in digital audio (and is the standard for compact discs).
• 44444 = repdigit
• 44583 = number of partitions of 41^[15]
• 44721 = smallest positive integer such that the expression ⁠1/n⁠ − ⁠1/n + 2⁠ ≤ 10⁻⁹
• 44724 = maximum number of days in which a human being has been verified to live (Jeanne Calment).^[16]
• 44944 = palindromic square

• 45360 = 26th highly composite number;^[17] smallest number with exactly 100 factors (including one and itself)

• 46080 = double factorial of 12
• 46233 = sum of the first eight factorials
• 46249 = 2nd number that can be written as in 3 ways^[18]
• 46368 = Fibonacci number^[19]
• 46656 = 216² = 36³ = 6⁶, 3-smooth number
• 46657 = Carmichael number^[6]
• 46972 = number of prime knots with 14 crossings

• 47058 = primary pseudoperfect number^[20]
• 47160 = 10-th derivative of x^x at x=1^[21]
• 47321/33461 ≈ √2

• 48629 = number of trees with 17 unlabeled nodes^[22]
• 48734 = number of 22-bead necklaces (turning over is allowed) where complements are equivalent^[23]

• 49151 = Woodall number^[24]
• 49152 = 3-smooth number
• 49726 = pentagonal pyramidal number
• 49940 = number of 21-bead binary necklaces with beads of 2 colors where the colors may be swapped but turning over is not allowed^[25]

There are 930 prime numbers between 40000 and 50000.