[6] It is one of the largest galaxies in the local universe, and possibly contains one of the most massive black holes known.

The black hole's mass is very uncertain, with estimates ranging from as low as 501 million M☉, to as high as 77.6 billion M☉.

However, this large number may be due to the addition of Intracluster globular clusters since the galaxy lies about 1 arcmin of the center of Abell 3558.

A black hole of this mass has a Schwarzschild radius of 1,530 AU (about 461 billion km in diameter).

Alternative calculations using the M-sigma relation and the newer core break radius method yielded estimates of 500 million M☉ and 27 billion M☉, respectively.