Like others on the autism spectrum, savants display a narrow repertoire of skills, which tend to be highly structured, rule-based, and nonverbal. Common savant domains include music, art, calendar calculating, lightning calculating, and mechanical/visual spatial skills. Most musical savants are blind and have perfect pitch, most artistic savants express themselves through realistic drawing and sculpture, and most rapid calculating savants have a fascination and facility with prime numbers. Even so, savants vary markedly in their abilities.