3-Butyl-2-propyl­amino-1-benzo­thieno[3,2-d]pyrimidin-4(3H)-one

In the title compound, C(17)H(21)N(3)OS, the propyl and butyl groups are disordered over two positions; site occupation factors are 0.304 (10) and 0.696 (10). The three fused rings are coplanar. In the crystal structure, inter­molecular N—H⋯O and C—H⋯O hydrogen bonds link the mol­ecules. Further stability is provided by offset π–π stacking inter­actions. Adjacent thienophene–pyrimidine and pyrimidine–benzene rings have centroid–centroid distances of 3.96 (1) and 3.55 (2) Å, respectively.