46893711600000 - what does this number signify?

46893711600000 is the number of seconds since "00:00:00 January 1, 1970." that it will take to get unlimited storage space on gmail ...:) If the javascript in the gmail login page is to be belived.

So we will get unlimited storage space in gmail at 01-02-3456 07:00:00 hours.

However, the year 2038 problem if not fixed in future versions of the browsers for Javascript the program will just fail. If you just google for 46893711600000 you will be surprised by the number of results you will get though.