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.
['2433', '41', 'F', 'A', 'c', '837', 'h', 'c', '6239', '2583', '8153', 'k', 'Z', 'g', '3483', 'R', '3387', 'p', '6401']