Q: What are the prime factors of the number 21,015,520?

 A: 2, 5, 19, 31, 223

Why are those the prime factors of the number 21,015,520?

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 21,015,520

21,015,520
Factor Arrows
210,507,760
Factor Arrows
25,253,880
Factor Arrows
22,626,940
Factor Arrows
21,313,470
Factor Arrows
2656,735
Factor Arrows
5131,347
Factor Arrows
196,913
Factor Arrows
31223

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, 31, 223

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 19 x 31 x 223 = 21,015,520

This can also be written as 25 x 51 x 191 x 311 x 2231 = 21,015,520

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


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