These Ids are arbitrary in one sense, and not so much on another.
Are you familiar with binary numbers?
The Id can be written in 15bit. For instance, your example, 16246, would be 011.1111.0111.0110. The ids start with 1 instead of 0 though, so 16246 would actually be represented by 011.1111.0111.0101.
The first eight digits are about Limit, MC Resolve, Outcome, Judgment, MC Growth, Driver, MC Approach, MC Problem-Solving Style - in that order. The rest is determined by domains, concerns, issues and stuff.
the "opposite" of 16246 (011.1111.0111.0101; steadfast, start, be-er, linear, decision, timelock, failure, bad, physics, learning, prerequisites, certainty) would be 16523 (100.0000.1000.1010; change, stop, do-er, holistic, action, optionlock, success, good, universe, the past, interdiction, inequity)
Basically, to get the "opposite", all you have to do is change all binary choices to their opposite. the rest is kinda arbitrary.
25579 - 110.0011.1110.1010 - steadfast, stop, be-er, holistic, decision, optionlock, success, good, psychology, becoming, commitment, avoidance
7190 - 001.1100.0001.0101 - change, start, do-er, linear, action, timelock, failure, bad, psychology, being, ability, accurate