Factor Calculator

Factors of 255

The factors of 255 are 1, 3, 5, 15, 17, 51, 85, and 255. In total, 255 has 8 factors. Its prime factorization is 3 × 5 × 17, and the sum of all its factors is 432.

All factors of 255

Here are all 8 factors of 255, listed from smallest to largest.

13515175185255

Factor pairs of 255

These 4 pairs of whole numbers each multiply to give 255.

1 × 255 = 255
3 × 85 = 255
5 × 51 = 255
15 × 17 = 255

Prime factorization of 255

Dividing 255 by the smallest prime at each step gives its prime factorization:

255 ÷ 3 = 85
85 ÷ 5 = 17
17 ÷ 17 = 1
Result: 255 = 3 × 5 × 17 = 3 × 5 × 17

The distinct prime factors of 255 are 3, 5, 17. To factorize any other number, use the prime factorization calculator.

Factor tree of 255

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

Factor tree of 255255385517
Prime factors are shown in solid indigo. Composite numbers split into their smallest prime and the quotient.

Properties of 255

Number of factors8
Sum of factors432
Sum of proper factors177
Prime factorization3 × 5 × 17
Prime or composite?Composite
Even or odd?Odd
Perfect square?No
Perfect cube?No
ClassificationDeficient

What makes 255 interesting

  • 255 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.
  • 255 is a deficient number: its proper factors sum to 177, which is 78 less than 255 itself.
  • 255 has 3 distinct prime factors (3, 5, 17), which is why it has so many divisors.

How to find the factors of 255 yourself

Divide 255 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 √255 ≈ 15.97, because every factor above that pairs with one below it.

255 ÷ 1 = 255 ✓
255 ÷ 3 = 85 ✓
255 ÷ 5 = 51 ✓
255 ÷ 15 = 17 ✓

Reading both columns gives every factor: 1, 3, 5, 15, 17, 51, 85, 255. The factor calculator does this automatically for any number.

Numbers mathematically connected to 255.

Frequently asked questions about 255

What are the factors of 255?

The factors of 255 are 1, 3, 5, 15, 17, 51, 85, and 255. That is 8 factors in total, counting both 1 and 255.

Is 255 a prime number?

No, 255 is not prime — it is a composite number with 8 factors. A prime number has exactly two factors, but 255 is also divisible by 3.

What is the prime factorization of 255?

The prime factorization of 255 is 3 × 5 × 17. Written out in full: 3 × 5 × 17 = 255. Its distinct prime factors are 3, 5, 17.

What two numbers multiply to give 255?

There are 4 pairs of whole numbers that multiply to 255: 1 × 255, 3 × 85, 5 × 51, 15 × 17.

What is the sum of the factors of 255?

Adding all the factors of 255 together gives 432. Excluding 255 itself, the proper factors sum to 177.

Is 255 a perfect square?

No, 255 is not a perfect square. There is no whole number that multiplies by itself to give 255. The nearest perfect squares are 225 and 256.

What is the largest factor of 255 other than itself?

The largest factor of 255 apart from 255 itself is 85, since 255 ÷ 85 = 3.

How many factors does 255 have?

255 has 8 factors: 1, 3, 5, 15, 17, 51, 85, and 255. You can verify this from the prime factorization 3 × 5 × 17: add 1 to each exponent and multiply, giving 2 × 2 × 2 = 8.

Explore more

Try another number in the factor calculator, break 255 down further with the prime factorization calculator, or compare 255 with another number using the GCF calculator and LCM calculator. For divisor counts and sums, see the divisor calculator.