Number

13

13 — Thirteen

13 is a prime, odd, a calendar year.

Thirteen is the sixth prime and is widely considered unlucky in many Western cultures (a phenomenon called triskaidekaphobia). It is also the smallest emirp — a prime whose digit reversal (31) is a different prime.

Sources https://en.wikipedia.org/wiki/13_(number)

Cousin Prime Curated Deficient Number Fibonacci Happy Number Prime Sexy Prime Squarefree Twin Prime

Properties

Parity: Odd
Digit count: 2
Digit sum: 4
Digital root: 4
Palindrome: No
Divisor count: 2
σ(n) — sum of divisors: 14

Primality

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

Divisors & multiples

All divisors (2)

1 · 13

Aliquot sum (sum of proper divisors): 1

Factor pairs (a × b = 13)

1 × 13

First multiples

13 · 26 · 39 · 52 · 65 · 78 · 91 · 104 · 117 · 130

Representations

In words: thirteen
Ordinal: 13th
Roman numeral: XIII
Binary: 1101
Octal: 15
Hexadecimal: D

Also seen as

Prime neighborhood

Adjacent primes:

Previous prime: 11 (gap of 2)
Next prime: 17 (gap of 4)

Pair status: twin with 11, cousin with 17.

ASCII character

As an ASCII codepoint, 13 is CR (carriage return). ASCII control character.

Hex color

#00000D

RGB(0, 0, 13)

IPv4 address

As an unsigned 32-bit integer, this is the IPv4 address 0.0.0.13.

Possible US bank routing number

This passes the ABA routing number checksum and matches the Federal Reserve numbering scheme.

Routing number

000000013

Federal Reserve

United States Government

Banks operate many routing numbers per state and division; an unmatched checksum-valid number can still be a real RTN at a smaller institution.

Look up 000000013 on FedACH ↗ Routing Number Lookup (Wise) ↗