Physicists showed that the generating function of orbifold elliptic genera of
symmetric orbifolds can be written as an infinite product. We show that there
exists a geometric factorization on space level behind this infinite product
formula, and we do this in the much more general framework of orbifold
mapping spaces, where factors in the infinite product correspond to finite
connected coverings of domain spaces whose fundamental groups are not
necessarily abelian. From this formula, a concept of geometric Hecke operators for
functors emerges. This is a nonabelian geometric generalization of the usual
Hecke operators. We show that these generalized Hecke operators indeed
satisfy the identity of the usual Hecke operators for the case of 2–dimensional
tori.