Q: What are the prime factors of the number 21,042,240?

 A: 2, 3, 5, 23, 953

Why are those the prime factors of the number 21,042,240?

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 21,042,240

21,042,240
Factor Arrows
210,521,120
Factor Arrows
25,260,560
Factor Arrows
22,630,280
Factor Arrows
21,315,140
Factor Arrows
2657,570
Factor Arrows
2328,785
Factor Arrows
3109,595
Factor Arrows
521,919
Factor Arrows
23953

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, 5, 23, 953

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 3 x 5 x 23 x 953 = 21,042,240

This can also be written as 26 x 31 x 51 x 231 x 9531 = 21,042,240

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


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