Let X be a variety of maximal Albanese dimension and of general type. Assume that q(X) = dim X, the Albanese variety Alb(X) is a simple abelian variety, and the bicanonical map is not birational. We prove that the Euler number χ(X, ω X ) is equal to 1, and |2K X | separates two distinct points over the same general point on Alb(X) via alb X (Theorem 1.1).