91Ó°ÊÓ

Find a reduced residue system modulo 12 consisting entirely of multiples of 5 .

Prove that if \(m>2\), then the sum of the numbers in any reduced residue system modulo \(m\) is a multiple of \(m\).

For which positive integers \(m\) is \(\phi(m)\) odd?

Solve a quadratic equation to find the primes \(p\) and \(q\), given that \(n=\) \(p q=4386607\) and \(\phi(n)=4382136\).

Show that every odd composite integer is a pseudoprime to base 1 and to base \(-1\).

Find a primitive root modulo \(19 .\) How many primitive roots modulo 19 are there?