View source for Suppose that a and b are positive integers for which a has 3 factors and b has a factors. If b is divisible by a, then what is the least possible value of b?

Suppose that <math>a</math> and <math>b</math> are positive integers for which <math>a</math> has <math>3</math> factors and <math>b</math> has <math>a</math> factors. If <math>b</math> is divisible by <math>a</math>, then what is the least possible value of $b?