### What is the greatest common factor of 57?

There is not a greatest common factor of a single number, such as 57, because there cannot be a greatest common factor without two or more numbers to compare. Common factors are factors that the numbers being compared have in common. The greatest common factor is the largest factor that all the numbers being compared have in common. The factors of 57 are 1, 3, 19, and 57. The prime factors of 57 are 3…