The Deshouillers–Dress–Tenenbaum theorem (or in short DDT theorem) is a result from probabilistic number theory, which describes the probability distribution of a divisor d {\displaystyle d} of a natural number n {\displaystyle n} within the interval [ 1 , n ] {\displaystyle [1,n]} , where the divisor d {\displaystyle d} is chosen uniformly. More precisely, the theorem deals with the sum of distribution functions of the logarithmic ratio of divisors to growing intervals. The theorem states that the Cesàro sum of the distribution functions converges to the arcsine distribution, meaning that small and large values have a high probability. The result is therefor also referred to as the arcsine law of Deshouillers–Dress–Tenenbaum.
The theorem was proven in 1979 by the French mathematicians Jean-Marc Deshouillers, François Dress, and Gérald Tenenbaum. The result was generalized in 2007 by Gintautas Bareikis and Eugenijus Manstavičius.