Greatest Common Factor of 441 and 447 = 3 Step 1: Find the prime factorization of 441 441 = 3 x 3 x 7 x 7 Step 2: Find the prime factorization of 447 447 = 3 x 149 Step 3: Multiply those factors both numbers have in common in steps i) or ii) above to find the gcf: GCF = 3 Step 4: Therefore, the greatest common factor of 441 and 447 is 3.