I am going to assume that the approximation we could achieve by assuming the validity of the Newtonian law of universal gravitation is satisfactory for your purposes, and that the object in question is mathematically equivalent to a morbidly obese American lounging on a beach in Bali--I.e., positioned at sea level and as close to the Equator as makes no difference. In that case, we take the equatorial radius E, rather than the polar radius P or the average radius A, as the best measure of the distance between the two bodies. Let G be the universal constant of gravitation. The answer you want is the product of 200G and the mass of the earth divided by E squared. We don't know the mass of the earth, but we can get it by multiplying E squared by 1960, the force on a 200Kg object at the equator according to WolframAlpha, and dividing by 200 times G. The rest of the calculation is trivial.
