A hemispherical bowl with a radius of 10.5 cm is joined to one end of a cylindrical pipe with the same diameter.  The combined shape is completely filled with water.  A pump is connected to the other end of the cylindrical pipe, capable of draining 1155 cm³ of water every minute. If the total height of the combined shape (hemisphere + cylinder) is 25.5 cm, determine the exact time, in minutes, it will take to empty the entire volume of water.