Find all factors, prime factors, and factor pairs of any number. Check if a number is prime.
This tool finds all the factors (divisors) of a given number — the whole numbers that divide into it evenly with no remainder. It's useful for math homework, simplifying fractions, and understanding number properties like whether a number is prime or composite.
The calculator checks each whole number from 1 up to the given number (or more efficiently, up to its square root, pairing factors) to determine which ones divide evenly, then lists them all.
Enter any positive whole number, and the calculator lists all of its factors.
Example: The factors of 24 are 1, 2, 3, 4, 6, 8, 12, and 24, since each of these numbers divides evenly into 24 with no remainder.
What's the difference between factors and prime factors? Factors include all numbers that divide evenly into a number, while prime factors are only the factors that are also prime numbers — every number's full factor list can be built by combining its prime factors in different ways.
Does every number have at least two factors? Every number greater than 1 has at least two factors: 1 and itself. Numbers with exactly these two factors are called prime numbers; numbers with more than two factors are called composite.
Why is 1 a factor of every number? Because any number divided by 1 always equals itself with no remainder, making 1 a universal factor.
How many factors does a perfect square have? Perfect squares (like 4, 9, 16, 25) always have an odd number of factors, because one factor pairs with itself (the square root) instead of a distinct partner.
What are factor pairs? Factor pairs are two numbers that multiply together to equal the original number — for 24, factor pairs include (1,24), (2,12), (3,8), and (4,6).