number.wiki
Number

66

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

Abundant Number Hexagonal Palindrome Repdigit Sphenic Number Squarefree Triangular Year

Properties

Parity
Even
Digit count
2
Digit sum
12
Digital root
3
Palindrome
Yes
Divisor count
8
σ(n) — sum of divisors
144

Primality

Prime factorization: 2 × 3 × 11

Divisors & multiples

All divisors (8)
1 · 2 · 3 · 6 · 11 · 22 · 33 · 66
Aliquot sum (sum of proper divisors): 78
Factor pairs (a × b = 66)
1 × 66
2 × 33
3 × 22
6 × 11
First multiples
66 · 132 · 198 · 264 · 330 · 396 · 462 · 528 · 594 · 660

Representations

In words
sixty-six
Ordinal
66th
Roman numeral
LXVI
Binary
1000010
Octal
102
Hexadecimal
42

Also seen as

Goldbach decomposition

Goldbach's conjecture says every even integer greater than 2 is the sum of two primes. For 66, here are decompositions:

  • 5 + 61 = 66
  • 7 + 59 = 66
  • 13 + 53 = 66
  • 19 + 47 = 66
  • 23 + 43 = 66
  • 29 + 37 = 66
ASCII character

As an ASCII codepoint, 66 is B. Printable ASCII character B.

Hex color
#000042
RGB(0, 0, 66)
IPv4 address

As an unsigned 32-bit integer, this is the IPv4 address 0.0.0.66.