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.
['X', 'g', '1069', 'N', 'c', 'h', '2553', 'O', 't', '6085', '763', 'v', '3473', 'c', 'm', '489', 'g', 'H', '2315', '9573']