The second largest prime divisor of an odd perfect number exceeds ten thousand
Abstract
Let sigma(n) denote the sum of positive divisors of the natural number n. Such a number is said to be perfect if sigma(n)=2n. It is well known that a number is even and perfect if and only if it has the form 2^(p1) (2^p1) where 2^p1 is prime. No odd perfect numbers are known, nor has any proof of their nonexistence ever been given. In the meantime, much work has been done in establishing conditions necessary for their existence. One class of necessary conditions would be lower bounds for the distinct prime divisors of an odd perfect number. For example, Cohen and Hagis have shown that the largest prime divisor of an odd perfect number must exceed 10^6, and Hagis showed that the second largest must exceed 10^3. In this paper, we improve the latter bound. In particular, we prove the statement in the title of this paper.
 Publication:

Mathematics of Computation
 Pub Date:
 1999
 Bibcode:
 1999MaCom..68.1749I