Coprime Submodules

Let R be a commutative ring with unity and let M be a unitary R-module. It is wellknown that a proper submodule N of an R-module M is called prime if whenever rR, xM, rxN implies xN or r  [N:M ], where [N:M]={rR: rMN}. M is called a prime module if R ann M = R ann N for all nonzero submodule N of M , equivalently M is a prime module iff (0) is a prime submodule