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.
['6131', 'N', '385', 'D', '8941', 's', 'Q', '8853', '7713', '3053', 'G', '8449', 'P', 'w', '4703', '3687', '7333', 'C', 'c', '4617']