of course the visible one. There is no proofable number for all the other variants.
The multiverses will need a further definition though, like, 4D or higher
All the verses lie in a bigger nD-verse (physicists aren't sure, how many... heard so many variants 'till now xD I wonder what's the most popular one right now...)
Also, for multiverses and co, if you look at the organisation from sub-atomic particles up to multiverses in a fractal way (basically different steps or energy-organisation, in the end), you might get a feel for true physical infinity - aka you'll need infints for that xD
btw, how I calculated it:
2^256 = 115,792,089,237,316,195,423,570,985,008,687,907,853,269,984,665,640,564,039,457,584,007,913,129,639,936
according to Wikipedia, the observable universe is (at least) 93 billion lightyears wide, giving you 8.79829142e26 m
the planck lenght is 1.616252457677754134112479120986938602161024299570340768391981149326239172011423107331e-35 m
that gives you 5.44363683916153986558256955253284561149987547345636819647387763841815866649485631321e+61 planck lenghts for the universe - a number, which uses 80.1102283639848214585003874928078361957640324308066140352606767812020598903014473186% of the available digits in a 256int.
Infact, to print out the whole number as int, you'd only need a 206int, but as that's not as nice as 256 (for computers), 256 could under circumstances (due to optimisation options) be faster than 206...
so, you still have a lot of free space for superuniversal scales