Cannot find "reverse saturation current" of base-emitter junction in the data-sheet
It's not presented.

You might be able to extract it by curve fitting Figure 4, which shows the typical relationship between \$V_{BE}\$ and \$I_C\$.

Even easier, you can find a SPICE model for 2n2222, which will likely include a reasonable value of \$I_{ES}\$ determined by a similar curve-fitting technique.