How does dvitype know the actual number of pages? dvitype reads the entire dvi file page by page, merely storing away the total_pages value from the postamble so it can report any discrepancy, not using it to actually parse the dvi file.
In theory it might be possible to change the tex4ht and t4ht programs to do the same, but this is not something I'm going to spend time on. Aside from the work of rearranging the basic logic of the programs, I think it's likely that some other capacity problem will arise. Seems much more reliable for Nasser to cut his documents down to something within range, and use some other method to combine them, as desired. I note that both dvips and dvipdfmx (didn't try others) behave like tex4ht, i.e., they only process the "modulo" pages, not the whole document. I've never thought much about TeX, the program. I assume that some variant It is Knuth who wrote this behavior in the first place. In original tex.web, he wrote this comment: If |total_pages>=65536|, the \.{DVI} file will lie. Original TeX effectively writes total_pages mod 65536. All other TeX variants inherited that behavior. What would groff, which also can write DVI, have done with a document having more than 2^16 pages? Since the postamble value in DVI format for total_pages is only two bytes, groff cannot represent a value >=2^16 either. Best, Karl P.S. Just for the archives, here is the tiny plain TeX file I wrote to generate a document with 65600 DVI pages: \count255=0 \loop\ifnum\count255 < 65600 \advance\count255 by 1 x\vfil\eject \repeat \end