Q: What are the prime factors of the number 21,500?

 A: 2, 5, 43

Why are those the prime factors of the number 21,500?

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 21,500

21,500
Factor Arrows
210,750
Factor Arrows
25,375
Factor Arrows
51,075
Factor Arrows
5215
Factor Arrows
543

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, 43

We can check our work by multiplying all of the prime factors together: 2 x 2 x 5 x 5 x 5 x 43 = 21,500

This can also be written as 22 x 53 x 431 = 21,500

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


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