# What is the Greatest Common Factor of 17 and 21?

Greatest common factor (GCF) of 17 and 21 is 1.

GCF(17,21) = 1

We will now calculate the prime factors of 17 and 21, than find the greatest common factor (greatest common divisor (gcd)) of the numbers by matching the biggest common factor of 17 and 21.

GCF Calculator and
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## How to find the GCF of 17 and 21?

We will first find the prime factorization of 17 and 21. After we will calculate the factors of 17 and 21 and find the biggest common factor number .

### Step-1: Prime Factorization of 17

Prime factors of 17 are 17. Prime factorization of 17 in exponential form is:

17 = 171

### Step-2: Prime Factorization of 21

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

21 = 31 × 71

### Step-3: Factors of 17

List of positive integer factors of 17 that divides 17 without a remainder.

1

### Step-4: Factors of 21

List of positive integer factors of 21 that divides 17 without a remainder.

1, 3, 7

#### Final Step: Biggest Common Factor Number

We found the factors and prime factorization of 17 and 21. The biggest common factor number is the GCF number.
So the greatest common factor 17 and 21 is 1.

Also check out the Least Common Multiple of 17 and 21

#### Related Greatest Common Factors of 21

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