You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
N-[(3S)-1,1-dioxothiolan-3-yl]-5-phenyl-N-(thiophen-2-ylmethyl)-2,3-dihydro-1,4-oxathiine-6-carboxamide is the IUPAC name of a molecule. Please give its molecular formula.
user
C20H21NO4S3
assistant