Math Problem

#include <stdio.h>
#include <math.h>

int is_int(long double x);

int main() {

    long double x;
    long int y, MAX=50000000;
    printf("\n\tSolutions: ");

    for (y = 1; y < MAX; y++ ) {
        x = sqrt(1141.0*y*y+1.0);
        if (is_int(x)) {
            printf("\t%ld", y);
        }
    }
    printf("\n\n");
    return 0;
}

int is_int (long double x) {

    if (floor(x) != x) {
        return 0;
    }
    else{
            return 1;
        }
}