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.
['4533', 'D', '823', 'a', 'x', 'p', '9787', '2587', 'T', 'Z', '2207', '8719', 'F', '7675', 'T', '2777', '203', 'N', 'o']