Atomic and nuclear properties of the neutron (n):

Quantity	Value	Units	Value	Units
Atomic number	0	n	n	n
Mass	+/- 1.008 664 916 00 (43)	u	+/- 939.565 379 (21)	MeV
Nuclear density	mmmfew x 1015	g cm-3	n	n

Mass values from 2010 CODATA
Mean life 880.0 ± 0.9 s (RPP2014; error includes scale factor of 1.8)