What is the Greatest Common Factor of 21978 and 21990?

Greatest common factor (GCF) of 21978 and 21990 is 6.

GCF(21978,21990) = 6

We will now calculate the prime factors of 21978 and 21990, than find the greatest common factor (greatest common divisor (gcd)) of the numbers by matching the biggest common factor of 21978 and 21990.

How to find the GCF of 21978 and 21990?

We will first find the prime factorization of 21978 and 21990. After we will calculate the factors of 21978 and 21990 and find the biggest common factor number .

Step-1: Prime Factorization of 21978

Prime factors of 21978 are 2, 3, 11, 37. Prime factorization of 21978 in exponential form is:

21978 = 2¹ × 3³ × 11¹ × 37¹

Step-2: Prime Factorization of 21990

Prime factors of 21990 are 2, 3, 5, 733. Prime factorization of 21990 in exponential form is:

21990 = 2¹ × 3¹ × 5¹ × 733¹

Step-3: Factors of 21978

List of positive integer factors of 21978 that divides 21978 without a remainder.

1, 2, 3, 6, 9, 11, 18, 22, 27, 33, 37, 54, 66, 74, 99, 111, 198, 222, 297, 333, 407, 594, 666, 814, 999, 1221, 1998, 2442, 3663, 7326, 10989

Step-4: Factors of 21990

List of positive integer factors of 21990 that divides 21978 without a remainder.

1, 2, 3, 5, 6, 10, 15, 30, 733, 1466, 2199, 3665, 4398, 7330, 10995

Final Step: Biggest Common Factor Number

We found the factors and prime factorization of 21978 and 21990. The biggest common factor number is the GCF number.
So the greatest common factor 21978 and 21990 is 6.

Also check out the Least Common Multiple of 21978 and 21990