Q: What are the prime factors of the number 21,402,405?

 A: 3, 5, 17, 101, 277

Why are those the prime factors of the number 21,402,405?

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 21,402,405

21,402,405
Factor Arrows
37,134,135
Factor Arrows
32,378,045
Factor Arrows
5475,609
Factor Arrows
1727,977
Factor Arrows
101277

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:

3, 5, 17, 101, 277

We can check our work by multiplying all of the prime factors together: 3 x 3 x 5 x 17 x 101 x 277 = 21,402,405

This can also be written as 32 x 51 x 171 x 1011 x 2771 = 21,402,405

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


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