Number
638
638 is a composite number, even, a calendar year.
Properties
- Parity
- Even
- Digit count
- 3
- Digit sum
- 17
- Digital root
- 8
- Palindrome
- No
- Divisor count
- 8
- σ(n) — sum of divisors
- 1,080
Primality
Prime factorization: 2 × 11 × 29
Divisors & multiples
Aliquot sum (sum of proper divisors):
442
Representations
- In words
- six hundred thirty-eight
- Ordinal
- 638th
- Roman numeral
- DCXXXVIII
- Binary
- 1001111110
- Octal
- 1176
- Hexadecimal
- 27E
Also seen as
Goldbach decomposition
Goldbach's conjecture says every even integer greater than 2 is the sum of two primes. For 638, here are decompositions:
- 7 + 631 = 638
- 19 + 619 = 638
- 31 + 607 = 638
- 37 + 601 = 638
- 61 + 577 = 638
- 67 + 571 = 638
- 97 + 541 = 638
- 139 + 499 = 638
Showing the first eight; more decompositions exist.
Unicode codepoint
ɾ
U+027E
Lowercase letter (Ll)
UTF-8 encoding: C9 BE (2 bytes).
Hex color
#00027E
RGB(0, 2, 126)
IPv4 address
As an unsigned 32-bit integer, this is the IPv4 address 0.0.2.126.