Factors Calculator
Enter a whole number to list all of its factors and factor pairs, its prime factorization, the number and sum of its divisors, and whether it is a perfect, abundant or deficient number.
Any whole number up to 9,007,199,254,740,991. Negative numbers use the same factors.
How to use the Factors Calculator
- Enter a whole number, for example 360.
- Read the factor count and the prime factorization at the top.
- See every factor in the list, with the prime factors highlighted.
- Check the factor pairs table and download it as CSV if needed.
- Copy the results to get the full factor list as text.
How the factors are found
The calculator first finds the prime factorization by dividing by 2, 3 and then numbers of the form 6k ± 1 up to the square root. If n = p₁a × p₂b × …, then every factor is a product p₁i × p₂j × … with 0 ≤ i ≤ a, 0 ≤ j ≤ b, and so on. That gives these formulas:
| Quantity | Formula | Example: 360 = 2³ × 3² × 5 |
|---|---|---|
| Number of factors d(n) | (a + 1)(b + 1)… | 4 × 3 × 2 = 24 |
| Sum of factors σ(n) | (1 + p + … + pᵃ) × … | 15 × 13 × 6 = 1,170 |
| Sum of proper factors | σ(n) − n | 1,170 − 360 = 810 (abundant) |
| Factor pairs | d(n) ÷ 2, rounded up | 12 pairs |
Reference: factors of common numbers
| Number | Factors | Count | Type |
|---|---|---|---|
| 12 | 1, 2, 3, 4, 6, 12 | 6 | Abundant |
| 24 | 1, 2, 3, 4, 6, 8, 12, 24 | 8 | Abundant |
| 28 | 1, 2, 4, 7, 14, 28 | 6 | Perfect |
| 36 | 1, 2, 3, 4, 6, 9, 12, 18, 36 | 9 | Abundant, perfect square |
| 48 | 1, 2, 3, 4, 6, 8, 12, 16, 24, 48 | 10 | Abundant |
| 60 | 1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 30, 60 | 12 | Abundant |
| 64 | 1, 2, 4, 8, 16, 32, 64 | 7 | Deficient, perfect square |
| 100 | 1, 2, 4, 5, 10, 20, 25, 50, 100 | 9 | Abundant, perfect square |
| 97 | 1, 97 | 2 | Prime (deficient) |
Numbers with many factors, such as 12, 60, 360 and 5040, are called highly composite numbers, which is why they are popular for measuring time and angles (60 minutes, 360 degrees).
Frequently asked questions
What are the factors of a number?
Factors (divisors) are the whole numbers that divide a number exactly, with no remainder. The factors of 12 are 1, 2, 3, 4, 6 and 12.
How do you find the number of factors?
Write the prime factorization, add 1 to each exponent and multiply. For 360 = 2³ × 3² × 5, the number of factors is (3 + 1) × (2 + 1) × (1 + 1) = 24.
What is a factor pair?
A factor pair is two factors that multiply to give the number. For 36 the pairs are 1 × 36, 2 × 18, 3 × 12, 4 × 9 and 6 × 6. A perfect square has one pair where both factors are equal, so it has an odd number of factors.
What is a perfect number?
A perfect number equals the sum of its proper factors (all factors except itself). 6 = 1 + 2 + 3 and 28 = 1 + 2 + 4 + 7 + 14 are perfect. The next ones are 496, 8128 and 33,550,336.
What are abundant and deficient numbers?
If the proper factors add up to more than the number, it is abundant (12: 1 + 2 + 3 + 4 + 6 = 16). If they add up to less, it is deficient (10: 1 + 2 + 5 = 8). Every prime number is deficient.
How many factors does a prime number have?
Exactly two: 1 and the number itself. The number 1 has only one factor, so it is neither prime nor composite.
Do negative numbers have factors?
Yes. A negative number has the same positive factors as its absolute value, and each one also has a negative partner, so −12 is divisible by ±1, ±2, ±3, ±4, ±6 and ±12.