Q: What are the prime factors of the number 21,406,240?

 A: 2, 5, 337, 397

Why are those the prime factors of the number 21,406,240?

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 21,406,240

21,406,240
Factor Arrows
210,703,120
Factor Arrows
25,351,560
Factor Arrows
22,675,780
Factor Arrows
21,337,890
Factor Arrows
2668,945
Factor Arrows
5133,789
Factor Arrows
337397

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, 337, 397

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 337 x 397 = 21,406,240

This can also be written as 25 x 51 x 3371 x 3971 = 21,406,240

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


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