Fan designs can come in a huge number of variations. Various manufactures will offer a large range of sizes of fans with varying numbers of blades and blade designs. If you get into the mode of system design where you need to select a fan to meet a particular cooling requirement then you really need to look at some manufacturer catalogs. It is rather surprising at the total number of models of fans made. I did a quick survey of just one product family of fans from manufacturer in a specific size and found a large range available for selection.
The parameters you select on do not necessarily focus in number of fan blades. Instead you would be focusing on size, voltage, rated current, speed, max air flow, max air pressure and noise level.
An example of the fans from Delta in their AFB series in the 60mm x 60mm size yield tremendous variety of selection.
(click here for larger image size)
The above set of fan models can be seen in the Delta Fan Catalogue at these links:
Just this single AFB series of fans from delta come in all these size selections:
And to put even more emphasis on the total number Delta is offering all these series of DC powered fans and blowers:
Note that I have no affiliation with Delta other than I've used their fans in some product designs.