A propeller driven airplane has a gross take-off weight of 4905 N with a wing area of 6.84 m². Assume that the wings are operating at the maximum C_L^3/2/C_D of 13, the propeller efficiency is 0.9 and the specific fuel consumption of the engine is 0.76 kg/kW-hr. Given that the density of air at sea level is 1.225 kg/m³ and the acceleration due to gravity is 9.81 m/s², the weight of the fuel required for an endurance of 18 hours at sea level is _______ N (round off to the nearest integer).