Q: What are the prime factors of the number 21,521,728?

 A: 2, 17, 131, 151

Why are those the prime factors of the number 21,521,728?

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 21,521,728

21,521,728
Factor Arrows
210,760,864
Factor Arrows
25,380,432
Factor Arrows
22,690,216
Factor Arrows
21,345,108
Factor Arrows
2672,554
Factor Arrows
2336,277
Factor Arrows
1719,781
Factor Arrows
131151

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, 17, 131, 151

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 17 x 131 x 151 = 21,521,728

This can also be written as 26 x 171 x 1311 x 1511 = 21,521,728

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


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