Eriosyce taltalensis ssp. echinus var. floccosa (AKA Neoporteria floccosa)
Sometimes I miss the simplicity of the old name; the new name becomes a bit of a mouth full. Quickly snapped this shot today as it's quite impressive.
We keep this cactus - along with most of our cacti - very dry during the winter. As it tends to be a bit rot prone, it needs excellent drainage, but we don't give it anything different than we use with all our cacti as our potting mix has excellent porosity.