Hans Ivar Riesel (May 28, 1929 in Stockholm – December 21, 2014) was a Swedish mathematician who discovered the 18th known Mersenne prime in 1957, using the computer BESK: this prime is 23217-1 and consists of 969 digits. He held the record for the largest known prime from 1957 to 1961, when Alexander Hurwitz discovered a larger one. Riesel also discovered the Riesel numbers as well as developing the Lucas–Lehmer–Riesel test. After having worked at the Swedish Board for Computing Machinery, he was awarded his Ph.D. from Stockholm University in 1969 for his thesis Contributions to numerical number theory, and in the same year joined the Royal Institute of Technology as a senior lecturer and associate professor.
- Riesel, Hans (1994). Prime numbers and computer methods for factorization. Progress in Mathematics. 126 (2nd ed.). Boston, MA: Birkhauser. ISBN 0-8176-3743-5. Zbl 0821.11001.
- Tattersall, James J. (2005). Elementary Number Theory in Nine Chapters (2nd ed.). Cambridge University Press. p. 141. ISBN 0-521-85014-2.
- Devlin, Keith J. (1999). Mathematics: The New Golden Age (2nd ed.). Columbia University Press. p. 14. ISBN 0231116381.
- Ny Teknik, 16 september 2008: Nytt primtalsrekord satt i dag
- NADA: Hans Riesel, läst 22 april 2009
- LIBRIS 1768091