Q: What is the prime factorization of the number 28,231,424?

 A:
  • The prime factors are: 2 x 2 x 2 x 2 x 2 x 2 x 2 x 2 x 13 x 17 x 499
    • or also written as { 2, 2, 2, 2, 2, 2, 2, 2, 13, 17, 499 }
  • Written in exponential form: 28 x 131 x 171 x 4991

Why is the prime factorization of 28,231,424 written as 28 x 131 x 171 x 4991?

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 28,231,424

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 28,231,424 by 2

28,231,424 ÷ 2 = 14,115,712 - No remainder! 2 is one of the factors!
14,115,712 ÷ 2 = 7,057,856 - No remainder! 2 is one of the factors!
7,057,856 ÷ 2 = 3,528,928 - No remainder! 2 is one of the factors!
3,528,928 ÷ 2 = 1,764,464 - No remainder! 2 is one of the factors!
1,764,464 ÷ 2 = 882,232 - No remainder! 2 is one of the factors!
882,232 ÷ 2 = 441,116 - No remainder! 2 is one of the factors!
441,116 ÷ 2 = 220,558 - No remainder! 2 is one of the factors!
220,558 ÷ 2 = 110,279 - No remainder! 2 is one of the factors!
110,279 ÷ 2 = 55,139.5 - There is a remainder. We can't divide by 2 evenly anymore. Let's try the next prime number
110,279 ÷ 3 = 36,759.6667 - This has a remainder. 3 is not a factor.
110,279 ÷ 5 = 22,055.8 - This has a remainder. 5 is not a factor.
110,279 ÷ 7 = 15,754.1429 - This has a remainder. 7 is not a factor.
...
Keep trying increasingly larger numbers until you find one that divides evenly.
...
110,279 ÷ 13 = 8,483 - No remainder! 13 is one of the factors!
8,483 ÷ 13 = 652.5385 - There is a remainder. We can't divide by 13 evenly anymore. Let's try the next prime number
8,483 ÷ 17 = 499 - No remainder! 17 is one of the factors!
499 ÷ 17 = 29.3529 - There is a remainder. We can't divide by 17 evenly anymore. Let's try the next prime number
499 ÷ 19 = 26.2632 - This has a remainder. 19 is not a factor.
499 ÷ 23 = 21.6957 - This has a remainder. 23 is not a factor.
499 ÷ 29 = 17.2069 - This has a remainder. 29 is not a factor.
...
Keep trying increasingly larger numbers until you find one that divides evenly.
...
499 ÷ 499 = 1 - No remainder! 499 is one of the factors!

The orange divisor(s) above are the prime factors of the number 28,231,424. If we put all of it together we have the factors 2 x 2 x 2 x 2 x 2 x 2 x 2 x 2 x 13 x 17 x 499 = 28,231,424. It can also be written in exponential form as 28 x 131 x 171 x 4991.

Factor Tree

Another way to do prime factorization is to use a factor tree. Below is a factor tree for the number 28,231,424.

28,231,424
Factor Arrows
214,115,712
Factor Arrows
27,057,856
Factor Arrows
23,528,928
Factor Arrows
21,764,464
Factor Arrows
2882,232
Factor Arrows
2441,116
Factor Arrows
2220,558
Factor Arrows
2110,279
Factor Arrows
138,483
Factor Arrows
17499

More Prime Factorization Examples

28,231,42228,231,42328,231,42528,231,426
21 x 31 x 4,705,2371111 x 891 x 28,837132 x 52 x 2711 x 463121 x 1571 x 89,9091

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