# Greatest Common Factor of 21 and 40

Greatest common factor (GCF) of 21 and 40 is 1.

GCF(21,40) = 1

We will now calculate the prime factors of 21 and 40, than find the greatest common factor (greatest common divisor (gcd)) of the numbers by matching the biggest common factor of 21 and 40.

GCF Calculator and

## Prime Factorization of 21

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

21 = 31 × 71

## Prime Factorization of 40

Prime factors of 40 are 2, 5. Prime factorization of 40 in exponential form is:

40 = 23 × 51

### Factors of 21

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

1, 3, 7

### Factors of 40

List of positive integer factors of 40 that divides 21 without a remainder.

1, 2, 4, 5, 8, 10, 20

### Greatest Common Factor

We found the factors and prime factorization of 21 and 40. The biggest common factor number is the GCF number.
So the greatest common factor 21 and 40 is 1.

Also check out the Least Common Multiple of 21 and 40