C-sharp major

C♯ major

Relative key	A♯ minor enharmonic: B♭ minor
Parallel key	C♯ minor
Dominant key	G♯ major enharmonic: A♭ major
Subdominant	F♯ major enharmonic: G♭ major
Enharmonic	D♭ major
Component pitches
C♯, D♯, E♯, F♯, G♯, A♯, B♯, C♯

C♯ major (or C-sharp major) is a major scale based on C♯, consisting of the pitches C♯, D♯, E♯, F♯, G♯, A♯, and B♯. Its key signature has seven sharps.

Its relative minor is A♯ minor (or enharmonically B♭ minor) and its parallel minor is C♯ minor.

The direct enharmonic equivalent of C♯ major is D♭ major.

...
Wikipedia