Aleksandr Yakovlevich Khinchin (or Khintchine) is best known as a mathematician in the fields of number theory and probability theory. He is responsible for Khinchin's constant and the Khinchin Levy constant (sometimes referred to as the Levy Khinchin constant). These are both constants used in the calculation of fraction or decimal expansions. Several constants have been subsequently calculated from the Khinchin constant including those of Robinson in 1971 looking at nonstandard analysis.

Aleksandr Yakovlevich Khinchin was born in Kondrovo in Russia in 1894. As a student at Moscow University he worked with Nikolai Lusin where they both studied number theory and probability, they also extended the large number work of Emile Borel. In 1927 Khinchin became Professor of Mathematics at Moscow University. The proof behind Khinchin's constant was published in 1934 in Continued fractions. Much of his work is summarised in his book of 1957 (English translation) Mathematical Foundations of Information Theory. This was published 2 years before his death in Moscow in 1959. Khinchin spent all of his academic life at Moscow University.