You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Under IUPAC nomenclature, a molecule named N-(cyanomethyl)-4-methyl-2-[3-(2-oxo-3H-1,3-benzothiazol-6-yl)phenyl]pentanamide is given. What is its corresponding molecular formula?
user
C21H21N3O2S
assistant