Q: What is the prime factorization of the number 17,418,870?

 A:
  • The prime factors are: 2 x 3 x 3 x 5 x 7 x 43 x 643
    • or also written as { 2, 3, 3, 5, 7, 43, 643 }
  • Written in exponential form: 21 x 32 x 51 x 71 x 431 x 6431

Why is the prime factorization of 17,418,870 written as 21 x 32 x 51 x 71 x 431 x 6431?

What is prime factorization?

Prime factorization or prime factor decomposition is the process of finding which prime numbers can be multiplied together to make the original number.

Finding the prime factors of 17,418,870

To find the prime factors, you start by dividing the number by the first prime number, which is 2. If there is not a remainder, meaning you can divide evenly, then 2 is a factor of the number. Continue dividing by 2 until you cannot divide evenly anymore. Write down how many 2's you were able to divide by evenly. Now try dividing by the next prime factor, which is 3. The goal is to get to a quotient of 1.

If it doesn't make sense yet, let's try it...

Here are the first several prime factors: 2, 3, 5, 7, 11, 13, 17, 19, 23, 29...

Let's start by dividing 17,418,870 by 2

17,418,870 ÷ 2 = 8,709,435 - No remainder! 2 is one of the factors!
8,709,435 ÷ 2 = 4,354,717.5 - There is a remainder. We can't divide by 2 evenly anymore. Let's try the next prime number
8,709,435 ÷ 3 = 2,903,145 - No remainder! 3 is one of the factors!
2,903,145 ÷ 3 = 967,715 - No remainder! 3 is one of the factors!
967,715 ÷ 3 = 322,571.6667 - There is a remainder. We can't divide by 3 evenly anymore. Let's try the next prime number
967,715 ÷ 5 = 193,543 - No remainder! 5 is one of the factors!
193,543 ÷ 5 = 38,708.6 - There is a remainder. We can't divide by 5 evenly anymore. Let's try the next prime number
193,543 ÷ 7 = 27,649 - No remainder! 7 is one of the factors!
27,649 ÷ 7 = 3,949.8571 - There is a remainder. We can't divide by 7 evenly anymore. Let's try the next prime number
27,649 ÷ 11 = 2,513.5455 - This has a remainder. 11 is not a factor.
27,649 ÷ 13 = 2,126.8462 - This has a remainder. 13 is not a factor.
27,649 ÷ 17 = 1,626.4118 - This has a remainder. 17 is not a factor.
...
Keep trying increasingly larger numbers until you find one that divides evenly.
...
27,649 ÷ 43 = 643 - No remainder! 43 is one of the factors!
643 ÷ 43 = 14.9535 - There is a remainder. We can't divide by 43 evenly anymore. Let's try the next prime number
643 ÷ 47 = 13.6809 - This has a remainder. 47 is not a factor.
643 ÷ 53 = 12.1321 - This has a remainder. 53 is not a factor.
643 ÷ 59 = 10.8983 - This has a remainder. 59 is not a factor.
...
Keep trying increasingly larger numbers until you find one that divides evenly.
...
643 ÷ 643 = 1 - No remainder! 643 is one of the factors!

The orange divisor(s) above are the prime factors of the number 17,418,870. If we put all of it together we have the factors 2 x 3 x 3 x 5 x 7 x 43 x 643 = 17,418,870. It can also be written in exponential form as 21 x 32 x 51 x 71 x 431 x 6431.

Factor Tree

Another way to do prime factorization is to use a factor tree. Below is a factor tree for the number 17,418,870.

17,418,870
Factor Arrows
28,709,435
Factor Arrows
32,903,145
Factor Arrows
3967,715
Factor Arrows
5193,543
Factor Arrows
727,649
Factor Arrows
43643

More Prime Factorization Examples

17,418,86817,418,86917,418,87117,418,872
22 x 791 x 1991 x 2771131 x 311 x 43,22313,0891 x 5,639123 x 971 x 22,4471

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