Q: What are the prime factors of the number 3,978,640?

 A: 2, 5, 41, 1213

Why are those the prime factors of the number 3,978,640?

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 3,978,640

3,978,640
Factor Arrows
21,989,320
Factor Arrows
2994,660
Factor Arrows
2497,330
Factor Arrows
2248,665
Factor Arrows
549,733
Factor Arrows
411,213

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, 41, 1213

We can check our work by multiplying all of the prime factors together: 2 x 2 x 2 x 2 x 5 x 41 x 1,213 = 3,978,640

This can also be written as 24 x 51 x 411 x 1,2131 = 3,978,640

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


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