C program to find next prime palindrome: a user will enter a number, and we have to find the least number greater than it which is a palindrome as well as prime. For example, if the input is 7 then the output will be 11 as it is a prime as well as a palindrome, if the input is 21 then the output will be 101. In the program, we check if a number is a palindrome and then check if it is prime as it takes less time as primes occur more frequently than palindromes.

## C programming code

#include <stdio.h> #include <math.h> int main() { long n, t, r = 0, c, d; printf("Enter an integer\n"); scanf("%ld", &n); while (1) { n++; t = n; // Calculating reverse of the number while(t) { r = r*10; r = r + t%10; t = t/10; } // If reverse equals original then it is a palindrome if (r == n) { d = (int)sqrt(n); /* Checking prime */ for (c = 2; c <= d; c++) { if (n%c == 0) break; } if (c == d+1) break; } r = 0; } printf("%ld\n",n); return 0; }

Download Next prime palindrome program.

Output of program: