  A theoretical study is presented on the odd-frequency spin-singlet pairing
that arises in nonuniform even-frequency superconductors as a consequence of
broken translation symmetry. The effect of the odd-frequency pairing on the
superfluid density and the spin susceptibility is analyzed by using the
quasiclassical theory of superconductivity. It is shown that (1) the superfluid
density is reduced by the formation of the odd-frequency singlet pairs and (2)
the odd-frequency pairing increases the spin susceptibility even though its
spin symmetry is singlet. The two unusual phenomena are related to each other
through a generalized Yosida formula by taking into account both the even- and
odd-frequency pairing effects.
