In this Letter, we report the structural, elastic, and quasiparticle band structure of cynauric triazide. The structural properties using a dispersion corrected method to treat van der Waals (vdW) forces offers a significant improvement in the description of the ground state properties. The predicted bulk modulus from the equation of state and the elastic constants are consistent and the magnitude lies in the order of secondary explosives. Then, the G(0)W(0) approximation is used to study the band structure and an indirect band gap of 6.33 eV is obtained. Finally, we have calculated the optical and detonation characteristics at ambient pressure.