Q: What are the prime factors of the number 21,745,128?

 A: 2, 3, 29, 157, 199

Why are those the prime factors of the number 21,745,128?

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 21,745,128

21,745,128
Factor Arrows
210,872,564
Factor Arrows
25,436,282
Factor Arrows
22,718,141
Factor Arrows
3906,047
Factor Arrows
2931,243
Factor Arrows
157199

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, 29, 157, 199

We can check our work by multiplying all of the prime factors together: 2 x 2 x 2 x 3 x 29 x 157 x 199 = 21,745,128

This can also be written as 23 x 31 x 291 x 1571 x 1991 = 21,745,128

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


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