Q: What are the prime factors of the number 21,237,440?

 A: 2, 5, 7, 19, 499

Why are those the prime factors of the number 21,237,440?

Prime factors are the prime numbers that can be multipled together to equal the original number. You find the factors by dividing by prime numbers. It is best shown by creating a Factor Tree.

Factor Tree for the number 21,237,440

21,237,440
Factor Arrows
210,618,720
Factor Arrows
25,309,360
Factor Arrows
22,654,680
Factor Arrows
21,327,340
Factor Arrows
2663,670
Factor Arrows
2331,835
Factor Arrows
566,367
Factor Arrows
79,481
Factor Arrows
19499

The numbers in bold above are the prime factors. If there are multiples, you only count them one time. This leads us to our prime factors of:

2, 5, 7, 19, 499

We can check our work by multiplying all of the prime factors together: 2 x 2 x 2 x 2 x 2 x 2 x 5 x 7 x 19 x 499 = 21,237,440

This can also be written as 26 x 51 x 71 x 191 x 4991 = 21,237,440

If you would like to know more, or need additional explanation, please review our prime factorization explanation.


More Examples

Here are some more numbers to try:

Try the factor calculator

Explore more about the number 21,237,440:


Ask a Question