even, composite · 18th positive integer
The number 18
18 is an even composite number. It is the 18th positive integer.
Quick reference
| Prime factorization | 2 × 3 × 3 |
| Divisors | 1, 2, 3, 6, 9, 18 |
| Binary | 10010 |
| Hexadecimal | 0x12 |
| Roman numeral | XVIII |
| Digit sum | 9 |
| Properties | even, composite |
Frequently asked
Is 18 a prime number?
No. 18 is composite. Its prime factorization is 2 × 3 × 3.
What are the factors of 18?
The factors (divisors) of 18 are 1, 2, 3, 6, 9, 18.
What is 18 in binary?
18 in binary is 10010. In hexadecimal it's 12.
What is 18 as a Roman numeral?
18 in Roman numerals is XVIII.
What's the digit sum of 18?
Adding the digits of 18: 1 + 8 = 9.