Q: What are the prime factors of the number 21,017,420?

 A: 2, 5, 19, 41, 71

Why are those the prime factors of the number 21,017,420?

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 21,017,420

21,017,420
Factor Arrows
210,508,710
Factor Arrows
25,254,355
Factor Arrows
51,050,871
Factor Arrows
1955,309
Factor Arrows
192,911
Factor Arrows
4171

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, 19, 41, 71

We can check our work by multiplying all of the prime factors together: 2 x 2 x 5 x 19 x 19 x 41 x 71 = 21,017,420

This can also be written as 22 x 51 x 192 x 411 x 711 = 21,017,420

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


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