You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
N-[6-(5-chloro-1,3-benzoxazol-2-yl)spiro[3.3]heptan-2-yl]-2-(1-methyl-5-oxopyrrolidin-3-yl)acetamide The above is the IUPAC name of a molecule. Write its molecular formula.
user
C21H24ClN3O3
assistant