What is the Greatest Common Factor of 21855 and 21861?

Greatest common factor (GCF) of 21855 and 21861 is 3.

GCF(21855,21861) = 3

We will now calculate the prime factors of 21855 and 21861, than find the greatest common factor (greatest common divisor (gcd)) of the numbers by matching the biggest common factor of 21855 and 21861.

How to find the GCF of 21855 and 21861?

We will first find the prime factorization of 21855 and 21861. After we will calculate the factors of 21855 and 21861 and find the biggest common factor number .

Step-1: Prime Factorization of 21855

Prime factors of 21855 are 3, 5, 31, 47. Prime factorization of 21855 in exponential form is:

21855 = 3¹ × 5¹ × 31¹ × 47¹

Step-2: Prime Factorization of 21861

Prime factors of 21861 are 3, 7, 347. Prime factorization of 21861 in exponential form is:

21861 = 3² × 7¹ × 347¹

Step-3: Factors of 21855

List of positive integer factors of 21855 that divides 21855 without a remainder.

1, 3, 5, 15, 31, 47, 93, 141, 155, 235, 465, 705, 1457, 4371, 7285

Step-4: Factors of 21861

List of positive integer factors of 21861 that divides 21855 without a remainder.

1, 3, 7, 9, 21, 63, 347, 1041, 2429, 3123, 7287

Final Step: Biggest Common Factor Number

We found the factors and prime factorization of 21855 and 21861. The biggest common factor number is the GCF number.
So the greatest common factor 21855 and 21861 is 3.

Also check out the Least Common Multiple of 21855 and 21861