You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
4-cyclopentyloxy-5-(4-methylsulfonylpiperazin-1-yl)-2-[3-(trifluoromethyl)phenyl]pyridazin-3-one The above is the IUPAC name of a molecule. Write its molecular formula.
user
C21H25F3N4O4S
assistant