What is the Greatest Common Factor of 1221 and 1239?

Greatest common factor (GCF) of 1221 and 1239 is 3.

GCF(1221,1239) = 3

We will now calculate the prime factors of 1221 and 1239, than find the greatest common factor (greatest common divisor (gcd)) of the numbers by matching the biggest common factor of 1221 and 1239.

How to find the GCF of 1221 and 1239?

We will first find the prime factorization of 1221 and 1239. After we will calculate the factors of 1221 and 1239 and find the biggest common factor number .

Step-1: Prime Factorization of 1221

Prime factors of 1221 are 3, 11, 37. Prime factorization of 1221 in exponential form is:

1221 = 3¹ × 11¹ × 37¹

Step-2: Prime Factorization of 1239

Prime factors of 1239 are 3, 7, 59. Prime factorization of 1239 in exponential form is:

1239 = 3¹ × 7¹ × 59¹

Step-3: Factors of 1221

List of positive integer factors of 1221 that divides 1221 without a remainder.

1, 3, 11, 33, 37, 111, 407

Step-4: Factors of 1239

List of positive integer factors of 1239 that divides 1221 without a remainder.

1, 3, 7, 21, 59, 177, 413

Final Step: Biggest Common Factor Number

We found the factors and prime factorization of 1221 and 1239. The biggest common factor number is the GCF number.
So the greatest common factor 1221 and 1239 is 3.

Also check out the Least Common Multiple of 1221 and 1239