The P atom in the title mol-ecule, C(19)H(31)N(2)O(2)P, is in a distorted tetra-hedral configuration with the bond angles in the range 101.48 (10)-118.58 (9)°. The N-H units have a syn orientation with respect to one another. In the crystal, mol-ecules are connected via two different inter-molecular N-H⋯O(P) hydrogen bonds into chains along the a axis in which the O atom of the P=O group acts as a double acceptor.