Factors of 256

256 has 9 factors: 1, 2, 4, 8, 16, 32, 64, 128 and 256. Its prime factorization is 2⁸.

Factor pairs of 256

Factor×FactorProduct
1×256256
2×128256
4×64256
8×32256
16×16256

Negative pairs work too: (−1) × (−256), (−2) × (−128), … = 256.

Number of factors
9
Factor pairs
5
Sum of factors
511
Prime or composite
Composite
Even or odd
Even
Perfect square
Yes (16²)
Prime factorization 2⁸

How to find the factors of 256

Test every whole number from 1 up to the square root of 256 (√256 ≈ 16.000). Each number that divides evenly gives you two factors at once: the divisor and the quotient.

  • 256 ÷ 1 = 256 — so 1 and 256 are factors
  • 256 ÷ 2 = 128 — so 2 and 128 are factors
  • 256 ÷ 3 = 85.333 — not a whole number
  • 256 ÷ 4 = 64 — so 4 and 64 are factors
  • 256 ÷ 5 = 51.2 — not a whole number
  • 256 ÷ 6 = 42.667 — not a whole number
  • 256 ÷ 7 = 36.571 — not a whole number
  • 256 ÷ 8 = 32 — so 8 and 32 are factors
  • 256 ÷ 9 = 28.444 — not a whole number
  • 256 ÷ 10 = 25.6 — not a whole number
  • 256 ÷ 11 = 23.273 — not a whole number
  • 256 ÷ 12 = 21.333 — not a whole number
  • 256 ÷ 13 = 19.692 — not a whole number
  • 256 ÷ 14 = 18.286 — not a whole number
  • 256 ÷ 15 = 17.067 — not a whole number
  • 256 ÷ 16 = 16 — so 16 and 16 are factors

Collecting both numbers from every successful division gives the complete list: 1, 2, 4, 8, 16, 32, 64, 128 and 256.

Prime factorization of 256

Divide by the smallest prime that fits, and keep going until the quotient is 1:

256 ÷ 2 = 128
128 ÷ 2 = 64
64 ÷ 2 = 32
32 ÷ 2 = 16
16 ÷ 2 = 8
8 ÷ 2 = 4
4 ÷ 2 = 2
2 ÷ 2 = 1

The primes you divided by give 256 = 2⁸. From the exponents you can also count the factors without listing them: (8 + 1) = 9.

Properties of 256

  • 256 is a composite number.
  • The sum of all its factors is 511; the sum of its proper factors (excluding 256) is 255, which makes it a deficient number (its proper factors add up to less than itself).
  • 256 is a perfect square: 16 × 16. Perfect squares always have an odd number of factors.
  • Multiples of 256 include 512, 768, 1,024, 1,280 and so on.

Factors vs. multiples

Factors of 256 are the numbers that divide into it; multiples of 256 are the numbers it divides into. Every number has a limited set of factors but infinitely many multiples. To work with any other number, use the factors calculator, or find shared factors with the GCF calculator.

Frequently asked questions

What are the factors of 256?

The factors of 256 are 1, 2, 4, 8, 16, 32, 64, 128 and 256. Each of these divides 256 with no remainder.

How many factors does 256 have?

256 has 9 positive factors, which form 5 factor pairs. Counting negative factors as well doubles that to 18.

What is the prime factorization of 256?

256 = 2⁸. Its distinct prime factors are 2.

Is 256 a prime number?

No. 256 is composite because it has 9 factors, more than the two a prime number has.