6.37x10^-30 coulomb-meters
The unit for dipole moments is the Debye which is 1x10^-21 C*m^2/s divided by the speed of light (299792458 m/s). So the conversion factor is
1x10^-21 C*m^2/s / 299792458 m/s = 3.33564095E-30 C*m
And converting 1.91 d to Cm gives
1.91 * 3.33564095E-30 C*m = 6.37x10^-30 coulomb-meters
