Q: What are the prime factors of the number 21,680,128?

 A: 2, 67, 79

Why are those the prime factors of the number 21,680,128?

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 21,680,128

21,680,128
Factor Arrows
210,840,064
Factor Arrows
25,420,032
Factor Arrows
22,710,016
Factor Arrows
21,355,008
Factor Arrows
2677,504
Factor Arrows
2338,752
Factor Arrows
2169,376
Factor Arrows
284,688
Factor Arrows
242,344
Factor Arrows
221,172
Factor Arrows
210,586
Factor Arrows
25,293
Factor Arrows
6779

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, 67, 79

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 67 x 79 = 21,680,128

This can also be written as 212 x 671 x 791 = 21,680,128

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


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