"A small C program to print the biggest prime number" | Fabrice Bellard - https://bellard.org/mersenne.html

prime.c

#include <stdio.h>

int m = 1811939329, N = 1, t[1 << 26] = {2}, a, * p, i, e = 73421233, s, c, U = 1;
void g(int d, int h) {
  for (i = s; i < 1 << 25; i *= 2) d = d * 1LL * d % m;
  for (p = t; p < t + N; p += s)
    for (i = s, c = 1; i; i--) a = p[s] * (h ? c : 1LL) % m, p[s] = (m * 1U + * p - a) * (h ? 1LL : c) % m, * p = (a * 1U + * p) % m, p++, c = c * 1LL * d % m;
}
int main() {
  while (e /= 2) {
    N *= 2;
    U = U * 1LL * (m + 1) / 2 % m;
    for (s = N; s /= 2;) g(136, 0);
    for (p = t; p < t + N; p++) * p = * p * 1LL ** p % m * U % m;
    for (s = 1; s < N; s *= 2) g(839354248, 1);
    for (a = 0, p = t; p < t + N;) a += * p << (e & 1), * p++ = a % 10, a /= 10;
  }
  while (! * --p);
  for (t[0]--; p >= t;) putchar(48 + * p--);
}