How many gallons (or litres if you preffer) would your tank hold and will it be planted heavily/have floating plants?
If your tank is large enough, several males would be fine together. In my experience, these fish are one of the most peaceful gouramies and it is very rarely that you come across an aggressive male. The males do like to set up a territory in amongst floating plants or plants growing near the surface and these fish do get to a good size (up to 5" usualy) so a spacious tank, not over-stocked and with a large-ish footprint (thereforesurface area) is reccomended.
I would say the ratio of females to males isn't as important in pearls but I generaly suggest 2 females to every male. If you want 6, 2 males and 4 females would work fine. Occasionaly you'll find an overly-aggressive male but switching this fish for another male and re-arranging the tank a little should solve this problem permanently.
Again though, the tank needs to be quite large - 6 adult pearls (regardless of sex) need around 40 gallons to be comfortable - especialy if your plan is for a community set-up in which case you don't want to over-stock or over-crowd.