Q: What are the prime factors of the number 20,997,760?

 A: 2, 5, 7, 43, 109

Why are those the prime factors of the number 20,997,760?

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 20,997,760

20,997,760
Factor Arrows
210,498,880
Factor Arrows
25,249,440
Factor Arrows
22,624,720
Factor Arrows
21,312,360
Factor Arrows
2656,180
Factor Arrows
2328,090
Factor Arrows
2164,045
Factor Arrows
532,809
Factor Arrows
74,687
Factor Arrows
43109

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, 43, 109

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 5 x 7 x 43 x 109 = 20,997,760

This can also be written as 27 x 51 x 71 x 431 x 1091 = 20,997,760

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


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