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

## C programming code

#include <stdio.h> #include <math.h> #define TRUE 1 int main() { long n, t, r = 0, c, d; printf("Enter an integer\n"); scanf("%ld", &n); /* n must be a natural number */ while (TRUE) { n++; t = n; /* Calculating reverse of number */ while(t) { r *= 10; /* Compound assignment operator r*=10 => r=r*10 */ r += t%10; t /= 10; } /* if reverse equals original then it is 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: