As with most computer systems the top (first) bit indicates the sign of the value thus $8FCB455C$ would be a negative number.
If you want to force the value positive regardless of the number of bytes, prefix the value with $00$.
->print DEC (ATH ("008FCB455C") )
2412463452
->print DEC ($00$ + ATH ("8FCB455C") )
2412463452