Volume, pressure and temperature of an ideal gas are V, P and T respectively.
If mass of molecule is m, then its density is [ $k_B = Boltzmann`s constant$]
$ PV = RT \Rightarrow PV = { M \over M_o } RT $
$ \therefore {PMo \over RT } ={ M \over V} = \rho $
$ \rho = { PMo \over RT} = {P \times m \times N_A \over RT} = { Pm \over \left( { R \over N_A} \right)} T = { Pm \over k_B T } $