Looks like a Peanut Cactus to me. There seems to be a bit of Latin name confusion, I'm not sure which is correct, but Echinopsis chamaecereus might be it.
Has it had any flowers?
They're a little softer than full-on-tough-low-desert cacti. They seem to like a little more water, bright light and warm temps.
Yours is young, they sprawl and spread as they grow.
The spines are soft so it may need some protection from herbivory--I can't keep them outdoors here, they get eaten.
