The planet that has the characteristics you've listed is Uranus.
- It is cold on its surface but is thought to have a hot core.
- Uranus has a system of rings, though it has 13 known rings rather than 11.
- It has 27 known moons, which includes the 21 you mentioned as a possible figure.
- Uranus is unique among the planets in that it rotates on its side, with an axial tilt of about 98 degrees.
So the best match among your options is Uranus.