You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(S)-[(2R,4S,5R)-5-ethyl-1-azoniabicyclo[2.2.2]octan-2-yl]-(6-methoxyquinolin-4-yl)methanol;sulfate is the IUPAC name of a molecule. Please give its molecular formula.
user
C20H27N2O6S-
assistant