# Greatest Common Factor of 12 and 21

Greatest common factor (GCF) of 12 and 21 is 3.

GCF(12,21) = 3

We will now calculate the prime factors of 12 and 21, than find the greatest common factor (greatest common divisor (gcd)) of the numbers by matching the biggest common factor of 12 and 21.

GCF Calculator and

## Prime Factorization of 12

Prime factors of 12 are 2, 3. Prime factorization of 12 in exponential form is:

12 = 22 × 31

## Prime Factorization of 21

Prime factors of 21 are 3, 7. Prime factorization of 21 in exponential form is:

21 = 31 × 71

### Factors of 12

List of positive integer factors of 12 that divides 12 without a remainder.

1, 2, 3, 4, 6

### Factors of 21

List of positive integer factors of 21 that divides 12 without a remainder.

1, 3, 7

### Greatest Common Factor

We found the factors and prime factorization of 12 and 21. The biggest common factor number is the GCF number.
So the greatest common factor 12 and 21 is 3.

Also check out the Least Common Multiple of 12 and 21

#### Related Greatest Common Factors of 21

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