I am thinking of a five-digit number composed of even digits. If I swap the digit in the third position $\mathrm{s}$ with any other, the number decreases. Furthermore, I will reveal that the first digit is double the last, and the second digit is double the second to last.

What number am I thinking of?

(M. Mach)

Hint. Can you compare the third digit with the others?
The number is composed of even digits, i.e., digits $0,2,4,6,8$, not necessarily all of them.

The property of digit swapping means that the digit in the third position is smaller than any of the preceding digits and simultaneously larger than any of the following ones.

The first two positions are occupied by even digits that are double some other even digits, i.e., some of $0,4,8$.

No even number can be inserted between 0 and 0, or between 4 and 2, that would be smaller than the first and simultaneously larger than the second. The only conceivable number, therefore, is 88644.