You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
5-[4-oxo-4-(1-phenylethylamino)butyl]-N-phenyl-1,3,4-thiadiazole-2-carboxamide The above is the IUPAC name of a molecule. Write its molecular formula.
user
C21H22N4O2S
assistant