odd, prime, Fibonacci · 13th positive integer
The number 13
13 is an odd prime number. It's known as famously considered unlucky in Western culture; a Fibonacci number. It is the 13th positive integer.
Quick reference
| Prime factorization | 13 (prime) |
| Divisors | 1, 13 |
| Binary | 1101 |
| Hexadecimal | 0xD |
| Roman numeral | XIII |
| Digit sum | 4 |
| Properties | odd, prime, Fibonacci |
Why 13 is notable
Famously considered unlucky in Western culture; a Fibonacci number.
Frequently asked
Is 13 a prime number?
Yes. 13 is prime — its only divisors are 1 and itself.
What are the factors of 13?
The factors (divisors) of 13 are 1, 13.
What is 13 in binary?
13 in binary is 1101. In hexadecimal it's D.
What is 13 as a Roman numeral?
13 in Roman numerals is XIII.
What's the digit sum of 13?
Adding the digits of 13: 1 + 3 = 4.