C-trevigintuple-sharp Major is written in the key of C♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯ Major.
According to the Theorytab database, Major keys, along with minor keys, are a common choice for popular songs. The three most important chords, built off the 1st, 4th and 5th scale degrees are all major chords (C♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯ Major, F♯ Major, and G♯ Major).
See the C♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯♯ Major Cheat Sheet for popular chords, chord progressions, downloadable midi files and more!