Leonhard Euler was a Swiss polymath who was active as a mathematician, physicist, astronomer, logician, geographer, music theorist and engineer. He founded the studies of graph theory and topology and
1753 portrait
1957 Soviet Union stamp commemorating the 250th birthday of Euler. The text says: 250 years from the birth of the great mathematician, academician Leonhard Euler.
Euler's grave at the Alexander Nevsky Monastery
Euler portrait on the sixth series of the 10 Franc banknote
Number theory is a branch of mathematics devoted primarily to the study of the integers and arithmetic functions. Number theorists study prime numbers as well as the properties of mathematical objects
The Babylonians demonstrated an early understanding of Pythagorean triples.
The Riemann hypothesis is of interest in analytic number theory.
Number theorists Paul Erdős and Terence Tao in 1985, when Erdős was 72 and Tao was 10
Riemann zeta function ζ(s) in the complex plane. The color of a point s gives the value of ζ(s): dark colors denote values close to zero and hue gives the value's argument.