yeah i think u r wrong. a geostationary satellite orbits at a height of 35800 odd kilometres, thats not its distance from the Earth's centre of gravity. so if you took 35800 and subtracted the other number then you would've gotten a height less than that of a geostationary orbit.
what i did was take the equation:
r3/T2 = Gm/4π2
we know that T = 24 hours = 86400 seconds
we know that m = mass of Earth = 6×1024 kg
we know that G = 6.67×10-11
manipulate the equation to make:
r = 3√[T2×(Gm/4π2)]
r = 42,297,523.87 m
now with this you find the height:
h = r - rE
h = 42,297,523.87 - (6.373×106) [it was somewhere around that anyway]
h = 35,924,523.87 m
h = 35,924.52 km
h = 3.592×104 km
that's what i did anyways.