Prime factor calculator

This Prime factor calculator can calculate the prime factors for large integers. A prime number is a natural number greater than 1 that only has two factors : one and itself.

Examples : 2, 3, 5, 7, 11, 13, 17, 19, . . .

Enter A number to Factorise
The Prime Factors are


This prime factorization calculator calculates prime factors using JavaScript.

How to calculate the prime factorization number?



For example we take the number 15, Since 15 ÷ 3 = 5, we know that 3 and 5 are factors of 15. 1 and 15 are also factors but we don’t use them here because when finding the prime factorization, we always use factors other than 1 and number itself. So the prime factorization of the number 15 is 3 times 5.

Think of the prime factorization of a number is the prime factors of the number that you multiply together to get the original number.

How this calculator works? For example we take the number 81, We need to divide 81 by prime numbers to find it’s factors.

81 ÷ 3 = 27 (27 * 3)
27 ÷ 3 = 9 (9 * 3 * 3)
9 ÷ 3 = 3 (3 * 3 * 3 * 3)

Factor, Prime Number & Prime Factorization

Those numbers that are multiplied together are called factors of the final number. Example :

9 X 5 = 45 9 and 5 are factors of 45
6 X 2 = 12 6 and 2 are factors of 12

What is Prime Number?

Prime numbers are numbers that cannot be factored. A prime number is a natural number greater than 1 that only has two factors : one and itself. Example : 17 is prime number because the only numbers that will divide it evenly are 1 and 17.

Other prime numbers are 2, 3, 5, 7, 11, 13 and many more, because they have only two factors itself and 1.

How to Calculate Prime Factorization?

To determine the prime factorization of a natural number, we need to find the prime numbers that when multiplied together give us the original number. We need to be careful not to confuse prime factorization with the factors of a number. Remember the factors of a number are any two numbers whose product give the original number, factors do not need to be prime.

Remember : Use this simple prime factorization calculator to find the prime factor.