Factors of 261
The factors of 261 are 1, 3, 9, 29, 87, and 261. In total, 261 has 6 factors. Its prime factorization is 3² × 29, and the sum of all its factors is 390.
All factors of 261
Here are all 6 factors of 261, listed from smallest to largest.
Factor pairs of 261
These 3 pairs of whole numbers each multiply to give 261.
Prime factorization of 261
Dividing 261 by the smallest prime at each step gives its prime factorization:
The distinct prime factors of 261 are 3, 29. To factorize any other number, use the prime factorization calculator.
Factor tree of 261
A factor tree shows the same prime factorization visually. Each composite branch splits until every endpoint is a prime number.
Properties of 261
| Number of factors | 6 |
|---|---|
| Sum of factors | 390 |
| Sum of proper factors | 129 |
| Prime factorization | 3² × 29 |
| Prime or composite? | Composite |
| Even or odd? | Odd |
| Perfect square? | No |
| Perfect cube? | No |
| Classification | Deficient |
What makes 261 interesting
- 261 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.
- 261 is a deficient number: its proper factors sum to 129, which is 132 less than 261 itself.
How to find the factors of 261 yourself
Divide 261 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 √261 ≈ 16.16, because every factor above that pairs with one below it.
Reading both columns gives every factor: 1, 3, 9, 29, 87, 261. The factor calculator does this automatically for any number.
Related numbers
Numbers mathematically connected to 261.
Frequently asked questions about 261
What are the factors of 261?
Is 261 a prime number?
What is the prime factorization of 261?
What two numbers multiply to give 261?
What is the sum of the factors of 261?
Is 261 a perfect square?
What is the largest factor of 261 other than itself?
How many factors does 261 have?
Explore more
Try another number in the factor calculator, break 261 down further with the prime factorization calculator, or compare 261 with another number using the GCF calculator and LCM calculator. For divisor counts and sums, see the divisor calculator.