It looks like peruvian torch to me. I'm not an expert at ID cacti though. I have a few baby 6'' torches, and i've seen bigger ones. I've heard there are other cacti that look very similar so I can't be sure. Did you get it from a trusted source or did you find it or what?
Just found this at a garden shop. I had heard you could find them unlabeled often, thought this one looked alot like peruvian torch, was hoping to get lucky. No worries if its not, I like to grow plants.
