You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Convert the IUPAC name of a molecule 2,8-diazaspiro[4.5]decan-8-yl-(3-ethoxy-5-phenylthiophen-2-yl)methanone;hydrochloride into molecular formula.
user
C21H27ClN2O2S
assistant