The series converges absolutely by the ratio test.
To find the number of terms needed, you need to calculate the value of the first term, less than10-6
As far as I know there is no EASY way to do that except to calculate values for k starting with some big number and work in whichever direction you need to go...you could I guess use the Simpson approximation to the factorial, but it won't help much. or even a table of factorials will be a help.