What is the Greatest Common Factor of 21987 and 21991?

Greatest common factor (GCF) of 21987 and 21991 is 1.

GCF(21987,21991) = 1

We will now calculate the prime factors of 21987 and 21991, than find the greatest common factor (greatest common divisor (gcd)) of the numbers by matching the biggest common factor of 21987 and 21991.

How to find the GCF of 21987 and 21991?

We will first find the prime factorization of 21987 and 21991. After we will calculate the factors of 21987 and 21991 and find the biggest common factor number .

Step-1: Prime Factorization of 21987

Prime factors of 21987 are 3, 7, 349. Prime factorization of 21987 in exponential form is:

21987 = 3² × 7¹ × 349¹

Step-2: Prime Factorization of 21991

Prime factors of 21991 are 21991. Prime factorization of 21991 in exponential form is:

21991 = 21991¹

Step-3: Factors of 21987

List of positive integer factors of 21987 that divides 21987 without a remainder.

1, 3, 7, 9, 21, 63, 349, 1047, 2443, 3141, 7329

Step-4: Factors of 21991

List of positive integer factors of 21991 that divides 21987 without a remainder.

Final Step: Biggest Common Factor Number

We found the factors and prime factorization of 21987 and 21991. The biggest common factor number is the GCF number.
So the greatest common factor 21987 and 21991 is 1.

Also check out the Least Common Multiple of 21987 and 21991