odd, composite, perfect square, palindrome · 9th positive integer
The number 9
9 is an odd composite number. It's known as the largest single digit. It is the 9th positive integer.
Quick reference
| Prime factorization | 3 × 3 |
| Divisors | 1, 3, 9 |
| Binary | 1001 |
| Hexadecimal | 0x9 |
| Roman numeral | IX |
| Digit sum | 9 |
| Properties | odd, composite, perfect square, palindrome |
Why 9 is notable
The largest single digit.
Frequently asked
Is 9 a prime number?
No. 9 is composite. Its prime factorization is 3 × 3.
What are the factors of 9?
The factors (divisors) of 9 are 1, 3, 9.
What is 9 in binary?
9 in binary is 1001. In hexadecimal it's 9.
What is 9 as a Roman numeral?
9 in Roman numerals is IX.
What's the digit sum of 9?
Adding the digits of 9: 9 = 9.