Q: What are the prime factors of the number 21,172,480?

 A: 2, 5, 7, 17, 139

Why are those the prime factors of the number 21,172,480?

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 21,172,480

21,172,480
Factor Arrows
210,586,240
Factor Arrows
25,293,120
Factor Arrows
22,646,560
Factor Arrows
21,323,280
Factor Arrows
2661,640
Factor Arrows
2330,820
Factor Arrows
2165,410
Factor Arrows
282,705
Factor Arrows
516,541
Factor Arrows
72,363
Factor Arrows
17139

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, 17, 139

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 2 x 2 x 5 x 7 x 17 x 139 = 21,172,480

This can also be written as 28 x 51 x 71 x 171 x 1391 = 21,172,480

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 21,172,480:


Ask a Question