A photon of frequency $\nu$ has a momentum associated with it. If $c$ is the velocity of light, the momentum is:

The energy of a photon is given by $E=h\nu$.Also, for a massless particle like a photon, the energy-momentum relation is $E=pc$, where $p$ is the momentum.Equating the two:
$$pc=h\nu$$
$$p=\frac{h\nu }{c}$$