number.wiki
Number

21,521

21,521 is a prime, odd.

Cousin Prime Deficient Number Prime Squarefree Twin Prime

Properties

Parity
Odd
Digit count
5
Digit sum
11
Digital root
2
Palindrome
No
Divisor count
2
σ(n) — sum of divisors
21,522

Primality

21,521 is prime. It has exactly two divisors: 1 and itself.

Divisors & multiples

All divisors (2)
1 · 21521
Aliquot sum (sum of proper divisors): 1
Factor pairs (a × b = 21,521)
1 × 21521
First multiples
21,521 · 43,042 · 64,563 · 86,084 · 107,605 · 129,126 · 150,647 · 172,168 · 193,689 · 215,210

Representations

In words
twenty-one thousand five hundred twenty-one
Ordinal
21521st
Binary
101010000010001
Octal
52021
Hexadecimal
5411

Also seen as

Prime neighborhood

Adjacent primes:

  • Previous prime: 21,517 (gap of 4)
  • Next prime: 21,523 (gap of 2)

Pair status: twin with 21523, cousin with 21517.

Unicode codepoint
U+5411
Other letter (Lo)

UTF-8 encoding: E5 90 91 (3 bytes).

Hex color
#005411
RGB(0, 84, 17)
IPv4 address

As an unsigned 32-bit integer, this is the IPv4 address 0.0.84.17.