An integer is any whole number (positive, negative, or zero) that does not have a fractional or decimal part. A whole number is a non-negative integer, meaning it cannot be negative.
From the options provided:
- -4 is an integer but not a whole number (because it's negative).
- 25 is both an integer and a whole number.
- 10 is both an integer and a whole number.
- 3.5 is neither an integer nor a whole number.
Thus, the answer is -4.