You might find this link interesting. https://youtu.be/9qKHCg-nYv8

Agreeing with parityanimal”flower is an awfully deep blue-violet color”. I can’t see the base of the bloom to be certain, and I’m only speculating here. If the cactus was sold that already “bloomed” with this kind flower, you might want to check out the practice of cactus growers/sellers often hot glue or pin Strawflower (Xerochrysum bracteatum)(they can also dried & dye with various colors) on different cactus plants. According to sources, strawflower has the ability to open & close even after harvested from the plant depending on the humidity. Check out these included links for varieties of cactus with glued flowers. As parityanimal had suggested, photo of open flower will help quickly. Again I’m only speculating. Best wishes! https://stillwaterlakedawnblog.files.wordpress.com/2015/10/flowers-at-home-depot.jpg

Perhaps some variety of hedgehog cactus, though that flower is an awfully deep blue-violet color. Difficult to tell. Perhaps when the flower opens up more you could post another pic?