Momentum but no mass, if I recall my physics correctly (low certainty).
Wait, hang on, we have access to an appreciable-chunk of the world's knowledge at our fingertips...
https://en.wikipedia.org/wiki/Photon - "Photons are massless[...]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[...]Current commonly accepted physical theories imply or assume the photon to be strictly massless"
Wait, hang on, we have access to an appreciable-chunk of the world's knowledge at our fingertips...
https://en.wikipedia.org/wiki/Photon - "Photons are massless[...]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[...]Current commonly accepted physical theories imply or assume the photon to be strictly massless"