The eldest of three brothers, von Neumann was born Neumann János Lajos (Hungarian names have the family name first) in Budapest, Hungary, to a Jewish family. His father was Neumann Miksa (Max Neumann), a lawyer who worked in a bank. His mother was Kann Margit (Margaret Kann). János, nicknamed "Jancsi" (Johnny), was an extraordinary prodigy. At the age of six, he could divide two 8-digit numbers in his head.
He entered the German speaking Lutheran Gymnasium in Budapest in 1911. In 1913 his father was rewarded with ennoblement for his service to the Austro-Hungarian empire, the Neumann family acquiring the Hungarian mark of Margittai, or the Austrian equivalent von. Neumann János therefore became János von Neumann, a name that he later changed to the German Johann von Neumann. After teaching as history's youngest Privatdozent of the University of Berlin from 1926 to 1930, he, his mother, and his brothers emigrated to the United States; this in the early 1930s, after Hitler's rise to power in Germany. He anglicized Johann to John, he kept the Austrian-aristocratic surname of von Neumann, whereas his brothers adopted surnames Vonneumann and Neumann (using the de Neumann form briefly when first in the US).
Although von Neumann unfailingly dressed formally, he enjoyed throwing extravagant parties and driving hazardously (frequently while reading a book, and sometimes crashing into a tree or getting arrested). He once reported one of his many car accidents in this way: "I was proceeding down the road. The trees on the right were passing me in orderly fashion at 60 miles per hour. Suddenly one of them stepped in my path." He was a profoundly committed hedonist who liked to eat and drink heavily (it was said that he knew how to count everything except calories), tell dirty stories and very insensitive jokes (for example: "bodily violence is a displeasure done with the intention of giving pleasure"), and persistently gaze at the legs of young women (so much so that female secretaries at Los Alamos often covered up the exposed undersides of their desks with cardboard.)
He received his Ph.D. in mathematics (with minors in experimental physics and chemistry) from the University of Budapest at the age of 23. He simultaneously earned his diploma in chemical engineering from the ETH Zurich in Switzerland at the behest of his father, who wanted his son to invest his time in a more financially viable endeavour than mathematics. Between 1926 and 1930 he was a private lecturer in Berlin, Germany.
By age 25 he had published 10 major papers, and by 30, nearly 36.
Von Neumann was invited to Princeton, New Jersey in 1930, and was one of four people selected for the first faculty of the Institute for Advanced Study (two of the others were Albert Einstein and Kurt Gödel), where he was a mathematics professor from its formation in 1933 until his death.
From 1936 to 1938 Alan Turing was a visitor at the Institute, where he completed a Ph.D. dissertation under the supervision of Alonzo Church at Princeton. This visit occurred shortly after Turing's publication of his 1936 paper "On Computable Numbers with an Application to the Entscheidungsproblem" which involved the concepts of logical design and the universal machine. Von Neumann must have known of Turing's ideas but it is not clear whether he applied them to the design of the IAS machine ten years later.
Von Neumann married twice. He married Mariette Kövesi in 1930. When he proposed to her, he was incapable of expressing anything beyond "You and I might be able to have some fun together, seeing as how we both like to drink." Von Neumann agreed to convert to Catholicism to placate her family and remained a Catholic until his death. The couple divorced in 1937. He then married Klara Dan in 1938. Von Neumann had one child, by his first marriage, a daughter named Marina. She is a distinguished professor of international trade and public policy at the University of Michigan.
Von Neumann was diagnosed with bone cancer or pancreatic cancer in 1957, possibly caused by exposure to radioactivity while observing A-bomb tests in the Pacific or in later work on nuclear weapons at Los Alamos, New Mexico. (Fellow nuclear pioneer Enrico Fermi had died of stomach cancer in 1954.) Von Neumann died within a few months of the initial diagnosis, in excruciating pain. The cancer had spread to his brain, inhibiting mental ability. When at Walter Reed Hospital in Washington, D.C., he invited Roman Catholic priest (Father Anselm Strittmatter), who administered him the last Sacraments. He died under military security lest he reveal military secrets while heavily medicated. John Von Neumann was buried at Princeton Cemetery in Princeton, Mercer County, New Jersey.
He wrote 150 published papers in his life; 60 in pure mathematics, 20 in physics, and 60 in applied mathematics. He was developing a theory of the structure of the human brain before he died.
Von Neumann entertained notions which would now trouble many. His love for meteorological prediction led him to dream of manipulating the environment by spreading colorants on the polar ice caps in order to enhance absorption of solar radiation (by reducing the albedo) and thereby raise global temperatures. He also favored a preemptive nuclear attack on the USSR, believing that doing so could prevent it from obtaining the atomic bomb.