438 bytes to print the biggest prime number (a cleaner version)

prime.c

// All credits go to Fabrice Bellard http://bellard.org/mersenne.html

#include <stdio.h>

int m=167772161,N=1,t[1<<25]={2},a,*p,i,e=34893349,s,c,U=1;

g(d,h) {
  for(i=s;i<1<<24;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+*p-a)*(h?1LL:c)%m,a+=*p,*p++=a%m,c=c*1LL*d%m;
}

main() {
  while(e/=2) {
    N*=2;U=U*1LL*(m+1)/2%m;
    for (s=N;s/=2;)g(17,0);
    for(p=t;p<t+N;p++)*p=*p*1LL**p%m*U%m;
    for(s=1;s<N;s*=2)
      g(29606852,1);
    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--);
}

/*
  Tested on a MacBook Air (1.8 GHz Intel Core i5)
  Results: http://dl.dropbox.com/u/47709433/biggest-prime-number
*/

$ gcc prime.c
$ ./a.out > results

After 01:25.8 minutes I got

http://dl.dropbox.com/u/47709433/biggest-prime-number

el buen fabrice bellard lo vuelve a hacer