Q: What are the factor combinations of the number 21,251,357?

 A:
Positive:   1 x 2125135737 x 57436153 x 4009691961 x 10837
Negative: -1 x -21251357-37 x -574361-53 x -400969-1961 x -10837


How do I find the factor combinations of the number 21,251,357?

Unfortunately, there's not simple formula to identifying all of the factors of a number and it can be a tedious process when trying to identify the divisors of larger numbers. To find the factor combinations of the number 21,251,357, it is easier to work with a table - it's called factoring from the outside in.

Outside in Factoring

We start by creating a table and writing 1 on the left side and then the number we're trying to find the factors for on the right side in a table. Then, below that, write the numbers as a negative as well.

1 21,251,357
-1 -21,251,357

Why are the negative numbers included?

When you multiply two negative numbers together, you get a positive number. That means both the positive and negative numbers are factors of 21,251,357.

Example:
1 x 21,251,357 = 21,251,357
and
-1 x -21,251,357 = 21,251,357
Notice both answers equal 21,251,357

With that explanation out of the way, let's continue. Next, we take the number 21,251,357 and divide it by 2:

21,251,357 ÷ 2 = 10,625,678.5

If the quotient is a whole number, then 2 and 10,625,678.5 are factors. In this case, the quotient is not a whole number. Don't write anything down and try the next divisor.

Here is what our table should look like at this step:

1 21,251,357
-1 -21,251,357

Now, we try dividing 21,251,357 by 3:

21,251,357 ÷ 3 = 7,083,785.6667

If the quotient is a whole number, then 3 and 7,083,785.6667 are factors. In this case, the quotient is not a whole number. Don't write anything down and try the next divisor.

Here is what our table should look like at this step:

1 21,251,357
-1 -21,251,357

Let's try dividing by 4:

21,251,357 ÷ 4 = 5,312,839.25

If the quotient is a whole number, then 4 and 5,312,839.25 are factors. In this case, the quotient is not a whole number. Don't write anything down and try the next divisor.

Here is what our table should look like at this step:

1 21,251,357
-1 21,251,357
Keep dividing by the next highest number until you cannot divide anymore.

If you did it right, you will end up with this table:

137531,96110,837400,969574,36121,251,357
-1-37-53-1,961-10,837-400,969-574,361-21,251,357

More Examples

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