will 18 3 overflow

If I use 18!:3'' to create a new object for every request in socket server,
assuming 20 request per second, and 18!:3'' using 4-byte integer
   (2^31)%(20*3600*24)
1242.76

That is it will overflow after about 1200 days. While this uptime is acceptable,
I'm curious to know what are the limits of 18!:3'' and will be rollover from 1
and recycle?

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regards,
bill