Is it ever okay to have a class as a collection of methods and no properties?

I'm writing a bunch of generic-but-related functions to be used by different objects. I want to group the functions, but am not sure if I should put them in a class or simply a flat library file.

MathML and Java

I've been doing some research for a mathematical Android related project I'd like to embark upon and I stumbled across for the first time MathML.