Q: What are the prime factors of the number 21,400,400?

 A: 2, 5, 7, 7643

Why are those the prime factors of the number 21,400,400?

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 21,400,400

21,400,400
Factor Arrows
210,700,200
Factor Arrows
25,350,100
Factor Arrows
22,675,050
Factor Arrows
21,337,525
Factor Arrows
5267,505
Factor Arrows
553,501
Factor Arrows
77,643

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, 7, 7643

We can check our work by multiplying all of the prime factors together: 2 x 2 x 2 x 2 x 5 x 5 x 7 x 7,643 = 21,400,400

This can also be written as 24 x 52 x 71 x 7,6431 = 21,400,400

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


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