Number theorists

Reinhold Strassmann (or Straßmann) (24 January 1893 in Berlin – late October 1944 in Auschwitz concentration camp) was a German mathematician who proved Strassmann's theorem. His Ph.D. advisor at University of Marburg was Kurt Hensel.
Born into a Jewish family, Strassmann refused to leave Nazi Germany, and he was eventually detained and deported to Theresienstadt concentration camp in 1943. On October 23, 1944, he was deported from Theresienstadt to Auschwitz concentration camp, where he was murdered soon after.He was the son of the forensic pathologist Fritz Strassmann.

Alfred Theodor Brauer (April 9, 1894 – December 23, 1985) was a German-American mathematician who did work in number theory. He was born in Charlottenburg, and studied at the University of Berlin. As he served Germany in World War I, even being injured in the war, he was able to keep his position longer than many other Jewish academics who had been forced out after Hitler's rise to power. In 1935 he lost his position and in 1938 he tried to leave Germany, but was not able to until the following year. He initially worked in the Northeast, but in 1942 he settled into a position at the University of North Carolina at Chapel Hill. A good deal of his works, and the Alfred T. Brauer library, would be linked to this university. He occasionally taught at Wake Forest University after he retired from Chapel Hill at 70. He died in North Carolina, aged 91.
He was the brother of the mathematician Richard Brauer, who was the founder of modular representation theory.

Helmut Hasse (German: [ˈhasə]; 25 August 1898 – 26 December 1979) was a German mathematician working in algebraic number theory, known for fundamental contributions to class field theory, the application of p-adic numbers to local class field theory and diophantine geometry (Hasse principle), and to local zeta functions.

Paul Epstein (July 24, 1871 – August 11, 1939) was a German mathematician. He was known for his contributions to number theory, in particular the Epstein zeta function.
Epstein was born and brought up in Frankfurt, where his father was a professor. He received his PhD in 1895 from the University of Strasbourg. From 1895 to 1918 he was a Privatdozent at the University in Strasbourg, which at that time was part of the German Empire. At the end of World War I the city of Strasbourg reverted to France, and Epstein, being German, had to return to Frankfurt.
Epstein was appointed to a non-tenured post at the university and he lectured in Frankfurt from 1919. Later he was appointed professor at Frankfurt. However, after the Nazis came to power in Germany he lost his university position. Because of his age (68) he was unable to find a new position abroad, and finally committed suicide by barbital overdose at Dornbusch, fearing Gestapo torture because he was a Jew.

Charles-Jean Étienne Gustave Nicolas, baron de la Vallée Poussin (French pronunciation: [ʃaʁl ʒɑ̃ etjɛn ɡystav nikɔla baʁɔ̃ də la vale pusɛ̃]; 14 August 1866 – 2 March 1962) was a Belgian mathematician. He is best known for proving the prime number theorem.
The King of Belgium ennobled him with the title of baron.

Joseph Louis François Bertrand (French pronunciation: [ʒozɛf lwi fʁɑ̃swa bɛʁtʁɑ̃]; 11 March 1822 – 5 April 1900) was a French mathematician whose work emphasized number theory, differential geometry, probability theory, economics and thermodynamics.