Vishik became friend with the number theorist Arnold Walfisz. De Koninck is an analytic number theorist. Dickson became the first great American algebraist and number theorist. Number theorist Louis J. Mordell joined the College in 1920. Another notable student was Kurt Mahler, the number theorist. Sirovich met Carole Hochman, a number theorist, at the Courant Institute. Tanja Lange is a German cryptographer and number theorist at the Eindhoven University of Technology. Carl Bernard Pomerance (born 1944 in Joplin, Missouri) is an American number theorist. Paul Leyland is a British number theorist who has studied integer factorization and primality testing. Dorothy Irene Wallace Andreoli is an American number theorist, mathematical biologist, and mathematics educator.