40,000

"40k" redirects here. For the tabletop game, see Warhammer 40,000. For the isotope ⁴⁰K, see Potassium-40.

← 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	${\stackrel {\delta }{\mathrm {M} }}$
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.

Selected numbers in the range 40001–49999

40001 to 40999

• 40320 = smallest factorial (8!) that is not a highly composite number
• 40425 = square pyramidal number
• 40585 = largest factorion
• 40678 = pentagonal pyramidal number
• 40755 = Triangular number, Pentagonal number, Hexagonal number, 390-gonal, 4077-gonal, and 13586-gonal number.
• 40804 = palindromic square

41000 to 41999

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

42000 to 42999

• 42680 = octahedral number
• 42875 = 35³
• 42925 = square pyramidal number

43000 to 43999

• 43261 = Markov number
• 43380 = number of nets of a dodecahedron
• 43390 = number of primes $\leq 2^{19}$.
• 43560 = pentagonal pyramidal number
• 43691 = Wagstaff prime
• 43777 = smallest member of a prime sextuplet

44000 to 44999

• 44044 = palindrome of 79 after 6 iterations of the "reverse and add" iterative process
• 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
• 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).
• 44944 = palindromic square

45000 to 45999

• 45360 = highly composite number; smallest number with exactly 100 factors (including one and itself)

46000 to 46999

• 46080 = double factorial of 12
• 46233 = sum of the first eight factorials
• 46249 = 2nd number that can be written as $a^{2}+b!$ in 3 ways
• 46368 = Fibonacci number
• 46656 = 216² = 36³ = 6⁶, 3-smooth number
• 46657 = Carmichael number
• 46972 = number of prime knots with 14 crossings

47000 to 47999

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

48000 to 48999

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

49000 to 49999

• 49151 = Woodall number
• 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

Primes

There are 930 prime numbers between 40000 and 50000.