Let $N$ be a Carmichael number , $p$ its smallest prime factor, $q$ its largest prime factor.
Which is the largest possible prime $p$, if the range $[p,q]$ only contains at most $20$ primes ?
The Carmichael number $43\times67\times89\times103\times127\times137$ has this property because there are $20$ primes in the range $[43,137]$. I did not find an example with $p>43$.
Can it be shown, that $p>43$ is impossible ?