You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Translate the chemical IUPAC name 3-[3-oxo-5-[(2-pyrrolidin-3-ylpropan-2-ylamino)methyl]-1H-isoindol-2-yl]piperidine-2,6-dione into its molecular formula.
user
C21H28N4O3
assistant