Question: what is the greatest common factor of the numbers 14 and 21?
Answer: Greatest Common Factor of 14 and 21. Greatest common factor (GCF) of 14 and 21 is 7. We will now calculate the prime factors of 14 and 21, than find the greatest common factor (greatest common divisor (gcd)) of the numbers by matching the biggest common factor of 14 and 21.