What is the Greatest Common Factor of 391 and 399?

Greatest common factor (GCF) of 391 and 399 is 1.

GCF(391,399) = 1

We will now calculate the prime factors of 391 and 399, than find the greatest common factor (greatest common divisor (gcd)) of the numbers by matching the biggest common factor of 391 and 399.

How to find the GCF of 391 and 399?

We will first find the prime factorization of 391 and 399. After we will calculate the factors of 391 and 399 and find the biggest common factor number .

Step-1: Prime Factorization of 391

Prime factors of 391 are 17, 23. Prime factorization of 391 in exponential form is:

391 = 17¹ × 23¹

Step-2: Prime Factorization of 399

Prime factors of 399 are 3, 7, 19. Prime factorization of 399 in exponential form is:

399 = 3¹ × 7¹ × 19¹

Step-3: Factors of 391

List of positive integer factors of 391 that divides 391 without a remainder.

1, 17, 23

Step-4: Factors of 399

List of positive integer factors of 399 that divides 391 without a remainder.

1, 3, 7, 19, 21, 57, 133

Final Step: Biggest Common Factor Number

We found the factors and prime factorization of 391 and 399. The biggest common factor number is the GCF number.
So the greatest common factor 391 and 399 is 1.

Also check out the Least Common Multiple of 391 and 399