odd, prime · 31st positive integer
The number 31
31 is an odd prime number. It is the 31st positive integer.
Quick reference
| Prime factorization | 31 (prime) |
| Divisors | 1, 31 |
| Binary | 11111 |
| Hexadecimal | 0x1F |
| Roman numeral | XXXI |
| Digit sum | 4 |
| Properties | odd, prime |
Frequently asked
Is 31 a prime number?
Yes. 31 is prime — its only divisors are 1 and itself.
What are the factors of 31?
The factors (divisors) of 31 are 1, 31.
What is 31 in binary?
31 in binary is 11111. In hexadecimal it's 1F.
What is 31 as a Roman numeral?
31 in Roman numerals is XXXI.
What's the digit sum of 31?
Adding the digits of 31: 3 + 1 = 4.