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Number

21,491

21,491 is a prime, odd.

Cousin Prime Deficient Number Happy Number Prime Squarefree Twin Prime

Properties

Parity
Odd
Digit count
5
Digit sum
17
Digital root
8
Palindrome
No
Divisor count
2
σ(n) — sum of divisors
21,492

Primality

21,491 is prime. It has exactly two divisors: 1 and itself.

Divisors & multiples

All divisors (2)
1 · 21491
Aliquot sum (sum of proper divisors): 1
Factor pairs (a × b = 21,491)
1 × 21491
First multiples
21,491 · 42,982 · 64,473 · 85,964 · 107,455 · 128,946 · 150,437 · 171,928 · 193,419 · 214,910

Representations

In words
twenty-one thousand four hundred ninety-one
Ordinal
21491st
Binary
101001111110011
Octal
51763
Hexadecimal
53F3

Also seen as

Prime neighborhood

Adjacent primes:

  • Previous prime: 21,487 (gap of 4)
  • Next prime: 21,493 (gap of 2)

Pair status: twin with 21493, cousin with 21487.

Unicode codepoint
U+53F3
Other letter (Lo)

UTF-8 encoding: E5 8F B3 (3 bytes).

Hex color
#0053F3
RGB(0, 83, 243)
IPv4 address

As an unsigned 32-bit integer, this is the IPv4 address 0.0.83.243.