You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
[(2R,3R,4R,5R)-5-(2-amino-7-ethyl-6-oxo-1H-purin-9-ium-9-yl)-3,4-di(propan-2-yloxy)oxolan-2-yl]methoxy-oxido-oxophosphanium The above is the IUPAC name of a molecule. Write its molecular formula.
user
C18H29N5O7P+
assistant