You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
N-[2-[6-amino-8-[(6-iodo-1,3-benzodioxol-5-yl)sulfanyl]purin-9-yl]ethyl]-3-methylbutanamide is the IUPAC name of a molecule. Please give its molecular formula.
user
C19H21IN6O3S
assistant