Acanthocereus tetragonus ‘Fairy Castles’ maybe? if so, it's a diminutive form of Acanthocereus tetragonus. I've read it's very unlikely for this form to bloom.

that's crazy! I have the slightest feeling it may be epiphyllum because I have a vague memory or the parent being a draped plant but I coincidentally did a post before this (not sure if you can find it thru my name) and it turns out I have another upstairs. the this plant is just so thick I can't imagine in hanging. what can I do to accelerate its growth? or is it just such a slow growing plant? I do recall the other upstairs taking years to do much and all the sudden it just took off and won't stop growing!

Noah, soon you'll be ready to cut that etiollated piece off and start a new plant with it (also, the original plant will grow out of it). That's, of course, only if you want to rid the plant of that curve. Normal growth will resume with enough sun. It's a nice plant. Pilosocereus have some of the bluest colours available, along with lateral wool and cephaliums and flowers smelling of freshly-shucked corn.

Yes, you should repot it. Don't divide it. Carefully take it out of the pot y and clean most of the soil from the roots, often there is soil around that will not come off, don't worry about that. Get another pot bigger by about an inch across the top. Make some cactus and succulent soil with 1 measure potting soil and 1 measure pumice or perlite. Plant the cactus letting the soil only come up to cover little more than the roots. The top of the soil should be 1/4 tp 1/2 an inch from the top of the pot.