Your example code seems to be missing punctuation between array elements.
The example (pseudo) code looks like the output from print_r()? (There shouldn't be square brackets around the array indices either) - but if this was executed as-is you'd get a fatal parse error, not "Is in array".
Is this being run on a 64-bit system? 97381816989 is outside the 32-bit integer range, so this is not going to be preserved on a 32-bit system. Although I don't think this should affect the immediate in_array() problem?!