Highly divisible positive integers
Source: IMO Shortlist 2005, N5
March 19, 2007
number theoryprime numbersprime factorizationIMO Shortlist
Problem Statement
Denote by the number of divisors of the positive integer . A positive integer is called highly divisible if for all positive integers .
Two highly divisible integers and with are called consecutive if there exists no highly divisible integer satisfying .
(a) Show that there are only finitely many pairs of consecutive highly divisible
integers of the form with .
(b) Show that for every prime number there exist infinitely many positive highly divisible integers such that is also highly divisible.