We will prove that the number 220227k is not sureño and has exactly 2022 sureño divisors (for every positive integer k).
Every power of 2 is sureño. Indeed, the divisors of 2k are 2j for j=0,…,k and dj−dj−1=2j−2j−1=2j−1 is a divisor of 2k. Therefore we have that the powers of 2 that divide 22022⋅7k are sureño, that is, 2,22,23,…,22022. We have showed that the number has 2022 sureño divisors.
It remains for us to prove that the other divisors as well as the number itself are not sureño. That is, we have to show that the numbers 2j⋅7k are not sureño for j≥0 and k≥1.
If j=0 then the first divisors of the number are 1 and 7. Hence the number is not sureño, since 7−1=6 is not a divisor of 2j⋅7k.
If j=1 then the first divisors of the number are 1, 2 and 7. Again, the number is not sureño, since 7−2=5 is not a divisor of 2j⋅7k.
Finally, if j≥2 then the first divisors of the number are 1, 2, 4 and 7. Hence the number is not sureño, since 7−4=3 is not a divisor of 2j⋅7k.
We have completed the proof.