You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(4S,5R)-1-(2-methoxyethyl)-5-(5-phenylsulfanylfuran-2-yl)-4-pyridin-2-ylimidazolidine-2-thione is the IUPAC name of a molecule. Please give its molecular formula.
user
C21H21N3O2S2
assistant