In this task, you are given an input list A. You need to find all the elements of the list that are numbers and calculate their sum.
['n', 'x', 'H', 'W', '5593', '723', '3967', '5927', '5527', '4043', '5201', 'q', '5893', '2619', 'b', 'd', 'U', 'Q', 'U']