The Excel Iseven function tests if an initial supplied number (or expression) evaluates to an even number, and if so, returns TRUE; Otherwise, the function returns FALSE.
The syntax of the function is:
Where the supplied 'number' argument can be a simple number, a formula that returns a numeric value, or a reference to a cell that contains a number.
Several examples of the Excel Iseven function are shown in the spreadsheet below. The spreadsheet on the left shows the formulas used and the spreadsheet on the right shows the results:
Formulas:

Results:

Note that the example in cell A1 shows that the Iseven function returns True for a zero value. Also, as seen in cell A6, an empty cell evaluates to zero and so the Iseven function also returns True in this case.
If you get an error from the Excel Iseven function this is likely to be the #VALUE! error:
#VALUE!    Occurs if the supplied number argument is not a numeric value 