Q: What are the prime factors of the number 21,131,520?

 A: 2, 3, 5, 5503

Why are those the prime factors of the number 21,131,520?

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 21,131,520

21,131,520
Factor Arrows
210,565,760
Factor Arrows
25,282,880
Factor Arrows
22,641,440
Factor Arrows
21,320,720
Factor Arrows
2660,360
Factor Arrows
2330,180
Factor Arrows
2165,090
Factor Arrows
282,545
Factor Arrows
327,515
Factor Arrows
55,503

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, 3, 5, 5503

We can check our work by multiplying all of the prime factors together: 2 x 2 x 2 x 2 x 2 x 2 x 2 x 2 x 3 x 5 x 5,503 = 21,131,520

This can also be written as 28 x 31 x 51 x 5,5031 = 21,131,520

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


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