Seven is the only real quantity D for which the equation 2n − D = x2 has more than two remedies for n and x organic. Especially, the equation 2n − 7 = x2 is called the Ramanujan–Nagell equation. Jahannam has 7 gates which can be open constantly. (Qur’an – https://emperorg937blv3.ourabilitywiki.com/user