A note on fractal strings and spacetime

A short discussion is presented on the role of Mersenne primes and even perfect numbers in fractal strings, Cantorian-fractal spacetime, spin structures on Riemann surfaces and the classification of consistent string theories. Since in principle the number of Mersenne primes should be infinite this entails that the family of consistent quantum string theories in higher dimensions than 26 could be infinite as well and, consequently, this could be the physical reason why the number of quantum-spacetime dimensions is infinite. The Tsallis entropy of fractal strings is constructed followed by the exact expression for the fractal string mass spectrum.