Lev Genrikhovich Schnirelmann (Russian: Лев Ге́нрихович Шнирельма́н), also Shnirelman, Shnirel'man (January 2, 1905 – September 24, 1938) was a Soviet mathematician who sought to prove Goldbach's conjecture. In 1931, using the Brun sieve, he proved that any natural number greater than 1 can be written as the sum of not more than 20 prime numbers.
His other fundamental work is joint with Lazar Lyusternik. Together, they developed the Lyusternik-Schnirelmann category, as it is called now, based on the previous work by Henri Poincaré, David Birkhoff, and Marston Morse. The theory gives a global invariant of spaces, and has led to advances in differential geometry and topology.
Schnirelmann graduated from Moscow State University (1925) and then worked in Steklov Mathematical Institute (1934–1938). His advisor was Nikolai Luzin.
According to Pontryagin's memoir, Schnirelmann committed suicide in Moscow.