Q: What are the prime factors of the number 21,518,379?

 A: 3, 17, 5209

Why are those the prime factors of the number 21,518,379?

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 21,518,379

21,518,379
Factor Arrows
37,172,793
Factor Arrows
32,390,931
Factor Arrows
3796,977
Factor Arrows
3265,659
Factor Arrows
388,553
Factor Arrows
175,209

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:

3, 17, 5209

We can check our work by multiplying all of the prime factors together: 3 x 3 x 3 x 3 x 3 x 17 x 5,209 = 21,518,379

This can also be written as 35 x 171 x 5,2091 = 21,518,379

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


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