You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-[6-(4-ethoxyphenyl)imidazo[2,1-b][1,3]thiazol-3-yl]-N-propan-2-ylacetamide The above is the IUPAC name of a molecule. Write its molecular formula.
user
C18H21N3O2S
assistant