Q: What are the prime factors of the number 21,756,672?

 A: 2, 3, 7, 19, 71

Why are those the prime factors of the number 21,756,672?

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 21,756,672

21,756,672
Factor Arrows
210,878,336
Factor Arrows
25,439,168
Factor Arrows
22,719,584
Factor Arrows
21,359,792
Factor Arrows
2679,896
Factor Arrows
2339,948
Factor Arrows
2169,974
Factor Arrows
284,987
Factor Arrows
328,329
Factor Arrows
39,443
Factor Arrows
71,349
Factor Arrows
1971

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, 3, 7, 19, 71

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 3 x 3 x 7 x 19 x 71 = 21,756,672

This can also be written as 28 x 32 x 71 x 191 x 711 = 21,756,672

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


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