Of what use is my code for finding prime numbers of a certain size?
I'm sorry to say that your code is likely to have essentially zero use.

Primes used for cryptography (e.g., RSA), are on the order of 2,048 and 4,096 bits of length, or respectively roughly 616 and 1,233 digits long. Algorithms already exist to rapidly find (random) primes of this size, and unless you've broken new ground in number theory, your approach is slower.

Additionally, the general trend lately is moving away from systems like RSA towards elliptic-curve based cryptosystems which have no need for the generation of primes.