The value of quantity 'G' in the law of gravitation: 

We know that any constant term is simply a constant value that is not dependent on the other parameters, such as Planck’s constant (h), Boltzmann constant (K), etc.

G is the universal constant of gravity, which doesn’t depend on the mass and radius of the earth.  G value is $6.67 \times {10}^{-11}{\mathrm{m}}^3{\mathrm{kg}}^{-1}{\mathrm{s}}^{-2}$.