Factors of 561

All factors of 561

Here are all 8 factors of 561, listed from smallest to largest.

Factor pairs of 561

These 4 pairs of whole numbers each multiply to give 561.

Prime factorization of 561

Dividing 561 by the smallest prime at each step gives its prime factorization:

The distinct prime factors of 561 are 3, 11, 17. To factorize any other number, use the prime factorization calculator.

Factor tree of 561

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

Properties of 561

What makes 561 interesting

• 561 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.
• 561 is a deficient number: its proper factors sum to 303, which is 258 less than 561 itself.
• 561 is a triangular number — it is the sum of the first 33 whole numbers (1 + 2 + … + 33 = 561).
• 561 has 3 distinct prime factors (3, 11, 17), which is why it has so many divisors.

How to find the factors of 561 yourself

Divide 561 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 √561 ≈ 23.69, because every factor above that pairs with one below it.

Reading both columns gives every factor: 1, 3, 11, 17, 33, 51, 187, 561. The factor calculator does this automatically for any number.