Q: What are the prime factors of the number 21,720,160?

 A: 2, 5, 7, 11, 41, 43

Why are those the prime factors of the number 21,720,160?

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 21,720,160

21,720,160
Factor Arrows
210,860,080
Factor Arrows
25,430,040
Factor Arrows
22,715,020
Factor Arrows
21,357,510
Factor Arrows
2678,755
Factor Arrows
5135,751
Factor Arrows
719,393
Factor Arrows
111,763
Factor Arrows
4143

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, 5, 7, 11, 41, 43

We can check our work by multiplying all of the prime factors together: 2 x 2 x 2 x 2 x 2 x 5 x 7 x 11 x 41 x 43 = 21,720,160

This can also be written as 25 x 51 x 71 x 111 x 411 x 431 = 21,720,160

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


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