83569

Appears in sequences

• Strong pseudoprimes to base 21.at n=21A020247
• Numbers k such that the continued fraction for sqrt(k) has odd period and if the last term of the periodic part is deleted the two central terms are both 23.at n=18A031611
• Numbers k such that phi(k) and cototient(k) are squares but k is not in A054755.at n=31A054756