I suggest you to check the next web site, where you can get more information related to your question:
wikipedia

Anyway, the answer to your question is:
Mass of proton : 1,6726 x 10^(-27) kg
Mass of neutron: 1,6749 x 10^(-27) kg
Mass of electron: 0,00091x10^(-27) kg

The mass of each particle is very small, as you might notice from the numbers.

As you see from this information, the mass of a neutron is greater than the mass of a proton because the neutron contains a proton, an electron, and some subatomic particles.