( For example , there are six divisors of four , 1 , 2 , 4 , -1 , -2 , -4 , but one would usually mention only the positive ones , 1 , 2 , and 4 . ) ( For example , there are six divisors of four , 1 , 2 , 4 , 1 , 2 , 4 , but only the positive ones would usually be mentioned , i.e. 1 , 2 , and 4 . )