  We propose general topological order parameters for interacting insulators in
terms of the Green's function at zero frequency. They provide an unified
description of various interacting topological insulators including the quantum
anomalous Hall insulators and the time reversal invariant insulators in four,
three and two dimensions. Since only Green's function at zero frequency is
used, these topological order parameters can be evaluated efficiently by most
numerical and analytical algorithms for strongly interacting systems.
