Q: What are the prime factors of the number 639,040?

 A: 2, 5, 1997

Why are those the prime factors of the number 639,040?

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 639,040

639,040
Factor Arrows
2319,520
Factor Arrows
2159,760
Factor Arrows
279,880
Factor Arrows
239,940
Factor Arrows
219,970
Factor Arrows
29,985
Factor Arrows
51,997

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, 1997

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 5 x 1,997 = 639,040

This can also be written as 26 x 51 x 1,9971 = 639,040

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


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