You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-amino-9-[8-(6-aminopurin-9-yl)-12-hydroxy-18-methoxy-3,3-dioxo-12-sulfanylidene-2,7,11,13,16-pentaoxa-3lambda6-thia-4-aza-12lambda5-phosphatricyclo[13.2.1.06,10]octadecan-17-yl]-1H-purin-6-one is the IUPAC name of a molecule. Please give its molecular formula.
user
C21H26N11O10PS2
assistant