You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
What is the molecular formula of the molecule identified by sodium;[[(2R,3R,4R,5R)-5-(6-aminopurin-9-yl)-3-hydroxy-4-phosphonooxyoxolan-2-yl]methoxy-oxidophosphoryl] [(3R,4S,5S)-5-(3-carboxypyridin-1-ium-1-yl)-3,4-dihydroxyoxolan-2-yl]methyl phosphate ?
user
C21H26N6NaO18P3
assistant