Answer
The mass of electron would be: 9.05 x $10^{-31}$ kg.
Work Step by Step
To find the mass of electron, we multiply the mass-to-charge ration with the charge of the electron:
m of electron = 5.64 X $10^{-12}$ $\frac{kg}{C}$ x 1.605 X $10^{-19}$ C
m of electron = 9.052 X $10^{-31}$ kg
m of electron = 9.05 X $10^{-31}$ kg