Q: What is the prime factorization of the number 20,771,788?

 A:
  • The prime factors are: 2 x 2 x 19 x 273,313
    • or also written as { 2, 2, 19, 273,313 }
  • Written in exponential form: 22 x 191 x 273,3131

Why is the prime factorization of 20,771,788 written as 22 x 191 x 273,3131?

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 20,771,788

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 20,771,788 by 2

20,771,788 ÷ 2 = 10,385,894 - No remainder! 2 is one of the factors!
10,385,894 ÷ 2 = 5,192,947 - No remainder! 2 is one of the factors!
5,192,947 ÷ 2 = 2,596,473.5 - There is a remainder. We can't divide by 2 evenly anymore. Let's try the next prime number
5,192,947 ÷ 3 = 1,730,982.3333 - This has a remainder. 3 is not a factor.
5,192,947 ÷ 5 = 1,038,589.4 - This has a remainder. 5 is not a factor.
5,192,947 ÷ 7 = 741,849.5714 - This has a remainder. 7 is not a factor.
...
Keep trying increasingly larger numbers until you find one that divides evenly.
...
5,192,947 ÷ 19 = 273,313 - No remainder! 19 is one of the factors!
273,313 ÷ 19 = 14,384.8947 - There is a remainder. We can't divide by 19 evenly anymore. Let's try the next prime number
273,313 ÷ 23 = 11,883.1739 - This has a remainder. 23 is not a factor.
273,313 ÷ 29 = 9,424.5862 - This has a remainder. 29 is not a factor.
273,313 ÷ 31 = 8,816.5484 - This has a remainder. 31 is not a factor.
...
Keep trying increasingly larger numbers until you find one that divides evenly.
...
273,313 ÷ 273,313 = 1 - No remainder! 273,313 is one of the factors!

The orange divisor(s) above are the prime factors of the number 20,771,788. If we put all of it together we have the factors 2 x 2 x 19 x 273,313 = 20,771,788. It can also be written in exponential form as 22 x 191 x 273,3131.

Factor Tree

Another way to do prime factorization is to use a factor tree. Below is a factor tree for the number 20,771,788.

20,771,788
Factor Arrows
210,385,894
Factor Arrows
25,192,947
Factor Arrows
19273,313

More Prime Factorization Examples

20,771,78620,771,78720,771,78920,771,790
21 x 72 x 791 x 2,683131 x 6,923,9291411 x 506,629121 x 31 x 51 x 132 x 171 x 2411

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