For the ground state, we have the nuclear spin I=1/2 hbar and a nuclear magnetic moment of -0.5943µN. This means -0.5943=gµN/2, because µ=gµNI/hbar so g=-0.5943*2=1.1886. g is dimensionless.
For the 245 keV level, we have I=5/2 hbar and µ=-0.766µN, so we have
g = 2*-0.766/5 = -0.3064.
A free electron has a spin 1/2, and a magnetic moment of 1 µB, so we have: g = 2*1/1 = 2.
The experimental value for g is 2.0023, due to interactions of the electron with virtual photons.
The neutron has a spin 1/2 hbar, its g-factor is -3.826, so we have a magnetic moment of -3.826/2 µN=-1.913 µN.