Type in GHC and shit bricks

Prelude> 2^182023232

>>13

Prelude> :i Double
data Double = GHC.Types.D# GHC.Prim.Double#
      -- Defined in GHC.Types
instance Enum Double -- Defined in GHC.Float
...

>>15
What is it then?  1.1 + ε where ε is required by Fractional?
Haskell Num is said to be broken, but it's still much much better than what I see in other languages.