E m13/C#
The E m13 chord consists of the E (Perfect unison), G (Minor third), B (Perfect fifth), D (Minor seventh), F# (Major ninth) and C# (Major thirteenth) notes, with C# as the bass note.

How to play the E m13/C# chord
- Play C# as the lowest bass note in the left hand
- Find E (Root) on the piano keyboard
- Add G (Minor third) — 3 semitones above E
- Add B (Perfect fifth) — 7 semitones above E
- Add D (Minor seventh) — 10 semitones above E
- Add F# (Major ninth) — 14 semitones above E
- Add C# (Major thirteenth) — 21 semitones above E
- Press all 7 notes simultaneously to sound the E m13/C# chord