👉 Weisenheimer is a term used in mathematics to describe an element that is neither prime nor composite. It was introduced by Carl Friedrich Gauss in 1837 and has since been widely studied in number theory, especially in relation to the distribution of primes and the distribution of composites. The Weisstein on Wolfram|Alpha provides a definition of "Weisenheimer": "In number theory, an element x is said to be Weisenheimer if it is neither prime nor composite."