English numbers aren't much harder.

    englishNumbers n = ten9 !! (n - 1)
      where infixr 7 <<>>
            (<<>>) = liftA2 (<>)
            ten1 = ["one", "two", "three", "four", "five", "six", "seven", "eight", "nine"]
            ten2 = ten1 <> ["ten", "eleven", "twelve"] <> (["thir", "four"] <> prefixes) <<>> ["teen"] <> (["twen", "thir", "for"] <> prefixes) <<>> ["ty"] <<>> ([[]] <> ten1)
              where prefixes = ["fif", "six", "seven", "eigh", "nine"]
            ten3 = ten2 <> ten1 <<>> ["hundred"] <<>> ([[]] <> ten2)
            ten6 = ten3 <> ten3 <<>> ["thousand"] <<>> ([[]] <> ten3)
            ten9 = ten6 <> ten3 <<>> ["million"] <<>> ([[]] <> ten6)