What is the Greatest Common Factor of 646 and 665?

Greatest common factor (GCF) of 646 and 665 is 19.

GCF(646,665) = 19

We will now calculate the prime factors of 646 and 665, than find the greatest common factor (greatest common divisor (gcd)) of the numbers by matching the biggest common factor of 646 and 665.

How to find the GCF of 646 and 665?

We will first find the prime factorization of 646 and 665. After we will calculate the factors of 646 and 665 and find the biggest common factor number .

Step-1: Prime Factorization of 646

Prime factors of 646 are 2, 17, 19. Prime factorization of 646 in exponential form is:

646 = 2¹ × 17¹ × 19¹

Step-2: Prime Factorization of 665

Prime factors of 665 are 5, 7, 19. Prime factorization of 665 in exponential form is:

665 = 5¹ × 7¹ × 19¹

Step-3: Factors of 646

List of positive integer factors of 646 that divides 646 without a remainder.

1, 2, 17, 19, 34, 38, 323

Step-4: Factors of 665

List of positive integer factors of 665 that divides 646 without a remainder.

1, 5, 7, 19, 35, 95, 133

Final Step: Biggest Common Factor Number

We found the factors and prime factorization of 646 and 665. The biggest common factor number is the GCF number.
So the greatest common factor 646 and 665 is 19.

Also check out the Least Common Multiple of 646 and 665