Factors of 91

All factors of 91

Here are all 4 factors of 91, listed from smallest to largest.

Factor pairs of 91

These 2 pairs of whole numbers each multiply to give 91.

Prime factorization of 91

Dividing 91 by the smallest prime at each step gives its prime factorization:

The distinct prime factors of 91 are 7, 13. To factorize any other number, use the prime factorization calculator.

Factor tree of 91

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

Properties of 91

What makes 91 interesting

• 91 is a composite number, meaning it has more than two factors. It can be written as a product of smaller whole numbers in 2 different ways.
• 91 is a deficient number: its proper factors sum to 21, which is 70 less than 91 itself.
• 91 is a triangular number — it is the sum of the first 13 whole numbers (1 + 2 + … + 13 = 91).

How to find the factors of 91 yourself

Divide 91 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 √91 ≈ 9.54, because every factor above that pairs with one below it.

Reading both columns gives every factor: 1, 7, 13, 91. The factor calculator does this automatically for any number.