piano chord
A♯sus4
A♯1D♯4E♯5
The third replaced by the fourth, which leans on the third it is standing in for.
Written the other way round it is B♭sus4 — the same twelve keys on a piano, a different piece of notation.
What is true of it
A♯sus4 is A♯, D♯ and E♯ — 1, 4 and 5 counted from A♯.
These are also the notes of D♯sus2/A♯ and E♭sus2/A♯. Which name is right depends on what is underneath and what came before — the notes alone do not decide.