number.wiki
Number

40

40 is a composite number, even, a calendar year.

Abundant Number Harshad / Niven Octagonal Year

Properties

Parity
Even
Digit count
2
Digit sum
4
Digital root
4
Palindrome
No
Divisor count
8
σ(n) — sum of divisors
90

Primality

Prime factorization: 2 3 × 5

Divisors & multiples

All divisors (8)
1 · 2 · 4 · 5 · 8 · 10 · 20 · 40
Aliquot sum (sum of proper divisors): 50
Factor pairs (a × b = 40)
1 × 40
2 × 20
4 × 10
5 × 8
First multiples
40 · 80 · 120 · 160 · 200 · 240 · 280 · 320 · 360 · 400

Representations

In words
forty
Ordinal
40th
Roman numeral
XL
Binary
101000
Octal
50
Hexadecimal
28

Also seen as

Goldbach decomposition

Goldbach's conjecture says every even integer greater than 2 is the sum of two primes. For 40, here are decompositions:

  • 3 + 37 = 40
  • 11 + 29 = 40
  • 17 + 23 = 40
ASCII character

As an ASCII codepoint, 40 is (. Printable ASCII character (.

Hex color
#000028
RGB(0, 0, 40)
IPv4 address

As an unsigned 32-bit integer, this is the IPv4 address 0.0.0.40.