A planetary roller screw comprising: a spindle having a male thread, a nut having a female thread, and planetary rollers arranged between the spindle and the nut and each including a male thread which engages both the male thread of the spindle and the female thread of the nut, wherein the spindle and the planetary rollers each include external toothing (8, 9), the external toothing of the spindle meshing with the external toothing of the planetary rollers, wherein the external toothing of the spindle is engaged in the male thread of the spindle and/or the external toothing of the planetary rollers is engaged in the male thread of the planetary rollers, so that the spindle and/or the planetary rollers include an overlapping section in which the respective male thread (5, 7) and the respective external toothing (8, 9) overlap such that a relative axial displacement between the spindle and the planetary rollers is enabled, wherein the planetary roller screw further includes a ring gear having internal toothing, wherein the nut is non-rotatable with respect to the ring gear, and wherein the external toothing of the planetary rollers meshes with the internal toothing of the ring gear, and wherein the planetary roller screw comprises a housing on which the spindle is rotatably supported, characterized in that the ring gear is non rotatable and axially displaceable with respect to the housing, wherein furthermore the nut is supported axially displaceably with respect to the ring gear, and wherein diameter ratios between spindle, planetary rollers and nut are selected such that, upon rotation of the spindle, both a relative axial displacement of the ring gear with respect to the housing and a relative axial displacement of the nut with respect to the ring gear take place. a spindle having a male thread, a nut having a female thread, and planetary rollers arranged between the spindle and the nut and each including a male thread which engages both the male thread of the spindle and the female thread of the nut, wherein the spindle and the planetary rollers each include external toothing (8, 9), the external toothing of the spindle meshing with the external toothing of the planetary rollers, wherein the external toothing of the spindle is engaged in the male thread of the spindle and/or the external toothing of the planetary rollers is engaged in the male thread of the planetary rollers, so that the spindle and/or the planetary rollers include an overlapping section in which the respective male thread (5, 7) and the respective external toothing (8, 9) overlap such that a relative axial displacement between the spindle and the planetary rollers is enabled, wherein the planetary roller screw further includes a ring gear having internal toothing, wherein the nut is non-rotatable with respect to the ring gear, and wherein the external toothing of the planetary rollers meshes with the internal toothing of the ring gear, and wherein the planetary roller screw comprises a housing on which the spindle is rotatably supported, characterized in that the ring gear is non rotatable and axially displaceable with respect to the housing, wherein furthermore the nut is supported axially displaceably with respect to the ring gear, and wherein diameter ratios between spindle, planetary rollers and nut are selected such that, upon rotation of the spindle, both a relative axial displacement of the ring gear with respect to the housing and a relative axial displacement of the nut with respect to the ring gear take place.