You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-cyanoethyl N-[2-[(2R,5R)-5-ethyl-4-[2-isocyanoethoxy(methyl)phosphanyl]oxy-2-(5-methyl-2,4-dioxopyrimidin-1-yl)oxolan-3-yl]oxyethyl]carbamate is the IUPAC name of a molecule. Please give its molecular formula.
user
C21H30N5O8P
assistant