During the (recently departed) matter-dominated era, the total mass of the Universe, including dark matter, is believed to have been fairly constant at around 1055 kg. This was the case in a time period from at least the CMB last scattering surface to nearly the present. Mass content is probably about the same now but it may be slowly decreasing due to dark energy. Anyhow, the total mass + energy of the observable Universe is currently probably within a factor of 10 of that. This is about 1063 Planck masses. Where did this very particular number come from? Did inflation simply say that this is a random initial condition? If this total mass (or total mass+energy) prediction was derived from fundamental constants, I think the prediction would require a dimensionless factor of 1063 somewhere. Does some model contain a number close to 1063?