3 x 17 = 51. Step 4: Repeat this process until there are no longer any prime factors larger than one to divide by. At the end, you should have the full list of factor pairs. Here are all the factor pairs for 51: (1, 51), (3, 17) So, to list all the factors of 51: 1, 3, 17, 51. The negative factors of 51 would be: -1, -3, -17, -51