You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
N-ethyl-4-(furan-2-carbonyl)-N'-[2-(4-hydroxy-3-methoxyphenyl)ethyl]piperazine-1-carboximidamide The above is the IUPAC name of a molecule. Write its molecular formula.
user
C21H28N4O4
assistant