You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-methyl-N-propyl-4-[1-(2-pyridin-3-ylacetyl)piperidin-4-yl]pyrimidine-5-carboxamide The above is the IUPAC name of a molecule. Write its molecular formula.
user
C21H27N5O2
assistant