A gear unit motor having a gear unit and an electric motor which drives the gear unit, the electric motor having a rotor shaft, which is disposed so as to allow a rotation about its rotor shaft axis, the gear unit having a first housing part and a second housing part, the second housing part having a square flange, the first housing part having a round flange facing the motor and a square flange facing the second gear unit housing part, in particular the square flange of the second housing part, the round flange and the square flange of the first housing part being connected by an interposed connection section, the connection section of the first housing part having projections in one surface section, in particular projections that extend parallel to the direction of the rotor shaft axis when viewed in the circumferential direction.