B Major 7#11, 3rd inversion (A# in the bass)
Also written as Bmaj7#11/A#.
Notes, from the bass up
A# (bass)E#BD#F#
The same notes as B Major 7#11 (A#, E#, B, D# and F#), rearranged so A# is the lowest note. Use it to move between chords with smaller jumps across the keyboard.