If the integer number a is divided by the non-zero integer number b, the quotient is an integer number and the remainder number is zero, We denote that a is divisible by b (or denote b divisible by a), denote b|a. Note that if b is 0, it is not called divisible.

Divisible property: (1) a is divisible by b, c is a arbitrarily integer number, then the product ac is divisible by b; (2) If a is divisible by both b and c, and b and c are prime, then a must be divisible by the product bc, and vice versa.