Q: What are the prime factors of the number 128,421,888?

 A: 2, 3, 7, 1493

Why are those the prime factors of the number 128,421,888?

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 128,421,888

128,421,888
Factor Arrows
264,210,944
Factor Arrows
232,105,472
Factor Arrows
216,052,736
Factor Arrows
28,026,368
Factor Arrows
24,013,184
Factor Arrows
22,006,592
Factor Arrows
21,003,296
Factor Arrows
2501,648
Factor Arrows
2250,824
Factor Arrows
2125,412
Factor Arrows
262,706
Factor Arrows
231,353
Factor Arrows
310,451
Factor Arrows
71,493

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, 1493

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 2 x 2 x 2 x 2 x 2 x 2 x 3 x 7 x 1,493 = 128,421,888

This can also be written as 212 x 31 x 71 x 1,4931 = 128,421,888

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


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