number.wiki
Number

691

691 is a prime, odd, a calendar year.

Deficient Number Prime Squarefree Year

Properties

Parity
Odd
Digit count
3
Digit sum
16
Digital root
7
Palindrome
No
Divisor count
2
σ(n) — sum of divisors
692

Primality

691 is prime. It has exactly two divisors: 1 and itself.

Divisors & multiples

All divisors (2)
1 · 691
Aliquot sum (sum of proper divisors): 1
Factor pairs (a × b = 691)
1 × 691
First multiples
691 · 1,382 · 2,073 · 2,764 · 3,455 · 4,146 · 4,837 · 5,528 · 6,219 · 6,910

Representations

In words
six hundred ninety-one
Ordinal
691st
Roman numeral
DCXCI
Binary
1010110011
Octal
1263
Hexadecimal
2B3

Also seen as

Prime neighborhood

Adjacent primes:

  • Previous prime: 683 (gap of 8)
  • Next prime: 701 (gap of 10)
Unicode codepoint
ʳ
U+02B3
Modifier letter (Lm)

UTF-8 encoding: CA B3 (2 bytes).

Hex color
#0002B3
RGB(0, 2, 179)
IPv4 address

As an unsigned 32-bit integer, this is the IPv4 address 0.0.2.179.