Answer
T = 84.5 ~minutes
This result does not depend on the mass of the satellite.
Work Step by Step
$T^2 = \frac{4 \pi^2 r^3}{GM}$
$T^2 = \frac{4 \pi^2 r}{g}$
$T = \sqrt{\frac{4 \pi^2 r}{g}} = 2\pi \sqrt{\frac{r}{g}} = 2\pi \sqrt{\frac{6.38 \times 10^6 ~m}{9.80 ~m/s^2}} $
$T = 5070~s = 84.5 ~minutes$
This result does not depend on the mass of the satellite.
