C 13b9, 3rd inversion (Bb in the bass)
Also written as C13b9/Bb.
Notes, from the bass up
Bb (bass)DbACEG
The same notes as C 13b9 (Bb, Db, A, C, E and G), rearranged so Bb is the lowest note. Use it to move between chords with smaller jumps across the keyboard.