3,637.4 × 3,630.6 km [2] Mean radius1,821.3 km (0.286 Earths) [2] Surface area 41,910,000 km 2  (0.082 Earths) Volume 2.53 × 10 10  km 3  (0.023 Earths) Mass 8.9319 × 10 22  kg (0.015 Earths)Mean  density 3.528 g/cm 3 Equatorial surface gravity 1.796  m/s 2  (0.183  g ) Escape velocity 2.558 km/s Rotation period synchronous Equatorial