You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Provide the molecular formula for the IUPAC named substance [4-[[2-(methoxymethyl)-5,6,7,8-tetrahydro-[1,2,4]triazolo[1,5-a]pyridin-8-yl]amino]-3-nitrophenyl]-phenylmethanone .
user
C21H21N5O4
assistant