Number
28
28 is a composite number, even, a calendar year.
Properties
- Parity
- Even
- Digit count
- 2
- Digit sum
- 10
- Digital root
- 1
- Palindrome
- No
- Divisor count
- 6
- σ(n) — sum of divisors
- 56
Primality
Prime factorization: 2 2 × 7
Divisors & multiples
Aliquot sum (sum of proper divisors):
28
Representations
- In words
- twenty-eight
- Ordinal
- 28th
- Roman numeral
- XXVIII
- Binary
- 11100
- Octal
- 34
- Hexadecimal
- 1C
Also seen as
Goldbach decomposition
Goldbach's conjecture says every even integer greater than 2 is the sum of two primes. For 28, here are decompositions:
- 5 + 23 = 28
- 11 + 17 = 28
ASCII character
As an ASCII codepoint, 28 is control character (0x1C). ASCII control character.
Hex color
#00001C
RGB(0, 0, 28)
IPv4 address
As an unsigned 32-bit integer, this is the IPv4 address 0.0.0.28.