Neutrinos occupy about 43% of the neutron mass, If the universe as a medium and large child, Neutrino accounted for 43% of total mass of the universe, It is the so-called "dark matter".

Each proton (or neutron) has about two thousand times the mass of an electron.

All the mass measurements that have been done to date of these neutron stars where you see the pulsations... all of them are very close to 1.4 solar mass.