2. The sum of three numbers is 121,526. One addend is the largest five-digit number, all digits of which are even; the second is the smallest four-digit number, all digits of which are odd. What is the third number?
2. We will sequentially consider all the conditions of the problem. Given that the first addend is a five-digit number, it follows that five digits will be used for its notation (XXXXX). Since it must be the largest and all its numbers are even, this will be the number 88888. The second addend is a four-digit number (XXXX), and since it is the smallest, all of its numbers are odd, so this will be 1111. By determining their sum $(88888+1111=89999)$, we can find the unknown addend. To do this, we subtract the sum of the two found addends from the known sum $(121526-89999=31527)$.

Answer: 31527.