You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
N,N-dimethyl-N'-(6-methyl-2-pyridin-4-ylpyrimidin-4-yl)-N'-propylpropane-1,3-diamine is the IUPAC name of a molecule. Please give its molecular formula.
user
C18H27N5
assistant