Macos sorts file randomly (at least it seems so to me)
The logic is simply that the file names you're looking at are sorted numerically. Finder takes the file names and note that they start with a number - everything up to first non-number character is then sorted numerically. 

I.e. from your example 9873613 &lt; 13480567 &lt; 39758380 &lt; 46432537 &lt; 81233033.

Note that some files have 7 digits, others have 8 digits.

In general Finder's sorting takes sequences of numeric digits and treat them as a single number to be sorted. Non-numeric parts are sorted alphabetically like you would expect. This system of collation is called "natural sorting".