As a reviewer, we see only numbers (our reviews are blind).  In the past, we were able to sort by number, and the arrow that is already present for the number column would indicate that the functionality is still there.  However, the sorting appeared to follow only the first digit and not the true number, which has wreaked havoc on our review system.  We provide a paper supplement for note taking, and the numbers of the applicants are in numerical order on the paper supplement (because we have always been able to sorty by numerical order of the student ID numbers every other year).