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.
['b', '3693', 'G', 'e', '4907', '5653', '3833', 'm', '8563', '8709', 'm', '2161', '4159', 'v', '6109', 'o', 'p', '6479']