Physics question below?

Question

Two spherical objects are separated by a distance of 3.60* 10^3 m. The objects are initially electrically neutral and are very small compared to the distance between them. Each object acquires the same negative charge due to the addition of electrons. As a result, each object experiences an electrostatic force that has a magnitude of 4.55* 10^21 N. How many electrons did it take to produce the charge on one of the objects?

Answer 1

F = (1/4πε)Q^2/R^2
Q = R√(4πεF)
R = 3.60*10^3 m
ε = 8.8541878176*10^-12
F = 4.55* 10^21 N
Q = 3.60*10^3 m√(4π(8.8541878176*10^-12 C^2/N-m^2)(4.55* 10^21 N))
Q = 2.56*10^9 Coulombs
Q = 2.56*10^9 Coul./1.602177e-19 Coul./electron
Q = 1.599*10^28 electrons