Q: What are the prime factors of the number 20,781,145?

 A: 5, 7, 11, 701

Why are those the prime factors of the number 20,781,145?

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 20,781,145

20,781,145
Factor Arrows
54,156,229
Factor Arrows
7593,747
Factor Arrows
784,821
Factor Arrows
117,711
Factor Arrows
11701

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:

5, 7, 11, 701

We can check our work by multiplying all of the prime factors together: 5 x 7 x 7 x 11 x 11 x 701 = 20,781,145

This can also be written as 51 x 72 x 112 x 7011 = 20,781,145

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


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