What is the Greatest Common Factor of 645 and 661?

Greatest common factor (GCF) of 645 and 661 is 1.

GCF(645,661) = 1

We will now calculate the prime factors of 645 and 661, than find the greatest common factor (greatest common divisor (gcd)) of the numbers by matching the biggest common factor of 645 and 661.

How to find the GCF of 645 and 661?

We will first find the prime factorization of 645 and 661. After we will calculate the factors of 645 and 661 and find the biggest common factor number .

Step-1: Prime Factorization of 645

Prime factors of 645 are 3, 5, 43. Prime factorization of 645 in exponential form is:

645 = 3¹ × 5¹ × 43¹

Step-2: Prime Factorization of 661

Prime factors of 661 are 661. Prime factorization of 661 in exponential form is:

661 = 661¹

Step-3: Factors of 645

List of positive integer factors of 645 that divides 645 without a remainder.

1, 3, 5, 15, 43, 129, 215

Step-4: Factors of 661

List of positive integer factors of 661 that divides 645 without a remainder.

Final Step: Biggest Common Factor Number

We found the factors and prime factorization of 645 and 661. The biggest common factor number is the GCF number.
So the greatest common factor 645 and 661 is 1.

Also check out the Least Common Multiple of 645 and 661