Deneb is a blue-white supergiant, around 200 times the diameter of the Sun, forming part of the Summer Triangle, along with Altair and Vega.
If it replaced the Sun in the solar system, its 'surface' would be around the position of Earth's orbit.
The Sun looks tiny, but of course Deneb is far from being the largest star. Its exact distance, and hence luminosity, has been difficult to calculate.
It is estimated to be between 55,000 and 196,000 times as luminous as the Sun. It is thought that it has now exhausted its supply of Hydrogen, and is in a cooling and expanding phase of its development. It will end its life as a Supernova.