As others have well stated, make sure there is no cotter key or "lock nut" or impediment to turning the nut; all you really need is the right size socket, breaker bar, cheater pipe if necessary, and the absolute resolve to win, even if it takes 1K or more of torque. I've done this by hand with the right size socket, breaker bar and 5' cheater pipe, which I bent but broke the nut loose.