Torque (lb.in) = 63,025 x Power (HP) / Speed (RPM)
Power (HP) = Torque (lb.in) x Speed (RPM) / 63,025
Torque (N.m) = 9.5488 x Power (kW) / Speed (RPM)
Power (kW) = Torque (N.m) x Speed (RPM) / 9.5488
References
http://www.wentec.com/unipower/calculators/power_torque.asp