Factors of 15
There are 4 factors of 15 — the full list is below, with factor pairs, prime factorization, and divisibility notes.
Factors of 15
1, 3, 5, 15
Factor pairs of 15
- 1 × 15
- 3 × 5
Prime factorization of 15
15 = 3 × 5
Number facts
- 15 is a composite number.
- 15 has 4 factors.
- 15 is not a perfect square.
- The sum of all factors of 15 is 24.
Divisibility rules that apply to 15
- 15 is divisible by 3 because the sum of its digits (6) is divisible by 3.
- 15 is divisible by 5 because it ends in 0 or 5.
Check another number
How the factors of 15 are calculated
To find the factors of 15, every whole number from 1 up to the square root of 15(about 3.87) is tested for even division. 15 is odd, and it divides evenly by 3, 5. Written as a product of primes, 15 = 3 × 5, which confirms every factor above is a combination of those prime building blocks.
Frequently asked questions about 15
How many factors does 15 have?
15 has 4 factors: 1, 3, 5, 15.
Is 15 a prime number?
No. 15 is composite because it has factors other than 1 and itself.
What are the factor pairs of 15?
The factor pairs of 15 are 1 × 15, 3 × 5.
What is the prime factorization of 15?
The prime factorization of 15 is 3 × 5.