The Schwarzschild Radius of a 40GM object is around 790AU, the orbit of Neptune is around 30AU. I’m sure the volume that the object can effect is beyond massive, but the “size” of a SMBH is defined by the point at which not even light can escape, the Schwarzschild Radius.
Still a Schwarzschild Radius of over 26 times the size of Neptune’s orbit is insane.