Factors of 18

All factors of 18

Here are all 6 factors of 18, listed from smallest to largest.

Factor pairs of 18

These 3 pairs of whole numbers each multiply to give 18.

Prime factorization of 18

Dividing 18 by the smallest prime at each step gives its prime factorization:

The distinct prime factors of 18 are 2, 3. To factorize any other number, use the prime factorization calculator.

Factor tree of 18

A factor tree shows the same prime factorization visually. Each composite branch splits until every endpoint is a prime number.

Properties of 18

What makes 18 interesting

• 18 is a composite number, meaning it has more than two factors. It can be written as a product of smaller whole numbers in 3 different ways.
• 18 is an abundant number: its proper factors sum to 21, which is 3 more than 18 itself.

How to find the factors of 18 yourself

Divide 18 by each whole number starting from 1. Whenever the division leaves no remainder, both the divisor and the quotient are factors. You only need to test up to √18 ≈ 4.24, because every factor above that pairs with one below it.

Reading both columns gives every factor: 1, 2, 3, 6, 9, 18. The factor calculator does this automatically for any number.