Q: What are the prime factors of the number 21,291,008?

 A: 2, 23, 113

Why are those the prime factors of the number 21,291,008?

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 21,291,008

21,291,008
Factor Arrows
210,645,504
Factor Arrows
25,322,752
Factor Arrows
22,661,376
Factor Arrows
21,330,688
Factor Arrows
2665,344
Factor Arrows
2332,672
Factor Arrows
2166,336
Factor Arrows
283,168
Factor Arrows
241,584
Factor Arrows
220,792
Factor Arrows
210,396
Factor Arrows
25,198
Factor Arrows
22,599
Factor Arrows
23113

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, 23, 113

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 2 x 2 x 2 x 2 x 2 x 23 x 113 = 21,291,008

This can also be written as 213 x 231 x 1131 = 21,291,008

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


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