Factors of 399

All factors of 399

Here are all 8 factors of 399, listed from smallest to largest.

Factor pairs of 399

These 4 pairs of whole numbers each multiply to give 399.

Prime factorization of 399

Dividing 399 by the smallest prime at each step gives its prime factorization:

The distinct prime factors of 399 are 3, 7, 19. To factorize any other number, use the prime factorization calculator.

Factor tree of 399

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

Properties of 399

What makes 399 interesting

• 399 is a composite number, meaning it has more than two factors. It can be written as a product of smaller whole numbers in 4 different ways.
• 399 is a deficient number: its proper factors sum to 241, which is 158 less than 399 itself.
• 399 has 3 distinct prime factors (3, 7, 19), which is why it has so many divisors.

How to find the factors of 399 yourself

Divide 399 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 √399 ≈ 19.97, because every factor above that pairs with one below it.

Reading both columns gives every factor: 1, 3, 7, 19, 21, 57, 133, 399. The factor calculator does this automatically for any number.