Q: What are the prime factors of the number 21,347,172?

 A: 2, 3, 7, 11, 17, 151

Why are those the prime factors of the number 21,347,172?

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 21,347,172

21,347,172
Factor Arrows
210,673,586
Factor Arrows
25,336,793
Factor Arrows
31,778,931
Factor Arrows
3592,977
Factor Arrows
3197,659
Factor Arrows
728,237
Factor Arrows
112,567
Factor Arrows
17151

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, 7, 11, 17, 151

We can check our work by multiplying all of the prime factors together: 2 x 2 x 3 x 3 x 3 x 7 x 11 x 17 x 151 = 21,347,172

This can also be written as 22 x 33 x 71 x 111 x 171 x 1511 = 21,347,172

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


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