Problem
NT-B1-M09-P018 Exactly Four Divisors
#18
★★★☆☆ Level 3 of 5
Describe all positive integers with exactly \(4\) positive divisors.
Write \(4\) as \(4\) and \(2\cdot2\).
If \(\tau(n)=4\), the possible exponent patterns are \(3\), or \(1\) and \(1\). Therefore \(n=p^3\) for a prime \(p\), or \(n=pq\), where \(p,q\) are distinct primes.
Repeats the example as a problem.