You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named N-tert-butyl-6-(4-chlorophenyl)-2-(4-ethylpiperazin-1-yl)imidazo[2,1-b][1,3,4]thiadiazol-5-amine by IUPAC nomenclature, provide its molecular formula.
user
C20H27ClN6S
assistant