You could try M. Ram Murty and Jody Esmonde, [Problems in Algebraic Number Theory][1] and/or M. Ram Murty [Problems in Analytic Number Theory][2]. 


  [1]: https://www.maa.org/press/maa-reviews/problems-in-algebraic-number-theory
  [2]: https://www.maa.org/publications/maa-reviews/problems-in-analytic-number-theory