photon

It has zero rest mass agreed............but it has energy as well........
so think now

energy is related to momentum ..
in empty space, the photon moves at c (the speed of light) and its energy and momentum are related by E = pc, where p is the magnitude of the momentum vector p. For comparison, the corresponding equation for particles with mass m is:
E²=p^2c2+m^2c4

The energy and momentum of a photon depend only on its frequency (ν) or equivalently, its wavelength (λ):
E=hc/λ

there is an error in previous post the c is not in power its is in multiplication