Q: What are the prime factors of the number 21,906?

 A: 2, 3, 1217

Why are those the prime factors of the number 21,906?

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 21,906

21,906
Factor Arrows
210,953
Factor Arrows
33,651
Factor Arrows
31,217

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, 1217

We can check our work by multiplying all of the prime factors together: 2 x 3 x 3 x 1,217 = 21,906

This can also be written as 21 x 32 x 1,2171 = 21,906

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


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