Factors of 15

The factors of 15 are 1, 3, 5, 15. It has 4 factors.

Factors of 15

Pick any whole number from 1 to 10,000.

15 = 3 \times 5

How to work it out

1
A factor of 15 is a whole number that divides it with nothing left over. You only need to test the numbers up to √15 ≈ 3.87; every one that divides gives a pair.
2
The factor pairs are listed in the table below. Together they give 4 factors.
3
Prime factorisation: keep dividing by the smallest prime that fits.
$15 = 3 \times 5$
4
Add all the factors: 1 + 3 + 5 + 15 = 24. Without 15 itself that is 9, so 15 is a deficient number.

LaTeX source of the formulas on this page

\[ 15 = 3 \times 5 \]

Factor	Pairs with	Product
1	15	1 × 15 = 15
3	5	3 × 5 = 15

What are the factors of 15?

The factors of 15 are 1, 3, 5, 15. It has 4 factors.

What are the prime factors of 15?

3, 5. As a product: 3 × 5.

How many factors does 15 have?

15 has 4 factors (2 factor pairs).

What is the sum of the factors of 15?

24.

Is 15 a prime number?

No. It is divisible by 3, so 15 = 3 × 5.