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Whopping Prime Number  September 17, 1985|LEE DEMBART | Times
Staff Writer  Computer scientists have accidentally stumbled on
the largest prime number ever discovered. It is the number 2
raised to the 216,091st power minus 1, which contains 65,050
digits and would fill two pages if printed in this newspaper.
Prime numbers are numbers that have no divisors other than
themselves and 1. For example, 13 is prime, but 14, which is the
product of 2 and 7, is not. The ancient Greeks knew that there
are an infinite number of primes, but no one has ever come up
with a formula for generating them.  While there is no known
practical use for 65,000-digit prime numbers, the method that
finds them requires trillions of calculations and is therefore a
useful test of the reliability of large supercomputers. It has
also engendered an informal competition among supercomputer
manufacturers for recognition as the fastest machines on the
market. The faster a computer