You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Can you give the molecular formula of the molecule (E)-3-(5-chloro-1-ethylindol-2-yl)-N-(2,2-dioxo-3,4-dihydro-1H-2lambda6,1-benzothiazin-5-yl)prop-2-enamide ?
user
C21H20ClN3O3S
assistant