Factors of 9
There are 3 factors of 9 — the full list is below, with factor pairs, prime factorization, and divisibility notes.
Factors of 9
1, 3, 9
Factor pairs of 9
- 1 × 9
- 3 × 3
Prime factorization of 9
9 = 3²
Number facts
- 9 is a composite number.
- 9 has 3 factors.
- 9 is a perfect square.
- The sum of all factors of 9 is 13.
Divisibility rules that apply to 9
- 9 is divisible by 3 because the sum of its digits (9) is divisible by 3.
- 9 is divisible by 9 because the sum of its digits (9) is divisible by 9.
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How the factors of 9 are calculated
To find the factors of 9, every whole number from 1 up to the square root of 9(about 3.00) is tested for even division. 9 is odd, and it divides evenly by 3. Written as a product of primes, 9 = 3². 9 is also a perfect square, which is why one of its factor pairs is a number multiplied by itself.
Frequently asked questions about 9
How many factors does 9 have?
9 has 3 factors: 1, 3, 9.
Is 9 a prime number?
No. 9 is composite because it has factors other than 1 and itself.
What are the factor pairs of 9?
The factor pairs of 9 are 1 × 9, 3 × 3.
What is the prime factorization of 9?
The prime factorization of 9 is 3².