Kaalut is a gigantic insectoid larva-like horror, dwelling in the nebulous realm of K'gil'mnon, along with the Gharoides, its parasitic insectoid servants it also likely has human worshippers.
Kaalut's powers vary but the most prominent are mind manipulation, telepathy, omniscience, invulnerability, immortality and possibly reality warping though this is not confirmed. Because of this, it may even rival Nyarlathotep in power. Kaalut's age is unknown though it is said to be as old as reality itself.
The cults who worship Kaalut are supposedly given supernatural powers that cannot be explained by regular science the Gharoides also might have the same abilities.
Even though Kaalut is an extremely powerful being, it is not related to Azathoth and it also seems to not be ruled by it either. But it wouldn't go against it that in K'gil'mnon, Kaalut may live outside reality.