What is the Greatest Common Factor of 21945 and 21956?

Greatest common factor (GCF) of 21945 and 21956 is 11.

GCF(21945,21956) = 11

We will now calculate the prime factors of 21945 and 21956, than find the greatest common factor (greatest common divisor (gcd)) of the numbers by matching the biggest common factor of 21945 and 21956.

How to find the GCF of 21945 and 21956?

We will first find the prime factorization of 21945 and 21956. After we will calculate the factors of 21945 and 21956 and find the biggest common factor number .

Step-1: Prime Factorization of 21945

Prime factors of 21945 are 3, 5, 7, 11, 19. Prime factorization of 21945 in exponential form is:

21945 = 3¹ × 5¹ × 7¹ × 11¹ × 19¹

Step-2: Prime Factorization of 21956

Prime factors of 21956 are 2, 11, 499. Prime factorization of 21956 in exponential form is:

21956 = 2² × 11¹ × 499¹

Step-3: Factors of 21945

List of positive integer factors of 21945 that divides 21945 without a remainder.

1, 3, 5, 7, 11, 15, 19, 21, 33, 35, 55, 57, 77, 95, 105, 133, 165, 209, 231, 285, 385, 399, 627, 665, 1045, 1155, 1463, 1995, 3135, 4389, 7315

Step-4: Factors of 21956

List of positive integer factors of 21956 that divides 21945 without a remainder.

1, 2, 4, 11, 22, 44, 499, 998, 1996, 5489, 10978

Final Step: Biggest Common Factor Number

We found the factors and prime factorization of 21945 and 21956. The biggest common factor number is the GCF number.
So the greatest common factor 21945 and 21956 is 11.

Also check out the Least Common Multiple of 21945 and 21956