Q: What are the prime factors of the number 21,878,528?

 A: 2, 7, 29, 421

Why are those the prime factors of the number 21,878,528?

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 21,878,528

21,878,528
Factor Arrows
210,939,264
Factor Arrows
25,469,632
Factor Arrows
22,734,816
Factor Arrows
21,367,408
Factor Arrows
2683,704
Factor Arrows
2341,852
Factor Arrows
2170,926
Factor Arrows
285,463
Factor Arrows
712,209
Factor Arrows
29421

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, 7, 29, 421

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 7 x 29 x 421 = 21,878,528

This can also be written as 28 x 71 x 291 x 4211 = 21,878,528

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


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