You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
[3-[1-[2-(diethylamino)ethyl]-4-hydroxy-5-oxo-3-propanoyl-2H-pyrrol-2-yl]phenyl] acetate is the IUPAC name of a molecule. Please give its molecular formula.
user
C21H28N2O5
assistant