How do I get the seed value sent to the Mersenne PRNG and convert to string?

My function contains this code:

random_device rd;   // non-deterministic generator
mt19937_64 gen(rd());
uniform_int_distribution<> dist(min, max);
return dist(gen);

I'm trying to write the seed to a string vector.

Can someone please teach me how to get the seed and convert it to a string?

Thanks!!