Divisor
In general, we say that m divides n for non-zero integers m and n, if and only if there exists an integer k such that n = km.  Thus, divisors can be negative as well as positive, although we often restrict our attention to positive divisors. (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.)