Products of hopfian manifolds and codimension-2 fibrators

We describe several conditions under which the product of hopfian manifolds is another hopfian manifold. As applications, the product F×A of a closed hopfian n-manifold F and a closed orientable aspherical m-manifold A is hopfian when either π1(F) is solvable and χ(A)≠0 or π1(F) is finite. Also, the product of any rational homology n-sphere Σn for which π1(Σn) is finite and a closed orientable n-manifold N with πi(N)=0 for 1<i<n−1 is hopfian. Using such facts we investigate conditions under which products of codimension-2 (orientable) fibrators are again codimension-2 (orientable) fibrators.