# Write a program in C language to Check a given number is Prime and Armstrong Number.

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In this program, two user-defined functions checkPrimeNumber() and checkArmstrongNumber() are created.

``````#include <stdio.h>
#include <math.h>
{
int i, flag = 1;
for(i=2; i<=n/2; ++i)
{

if(n%i == 0) // condition for non-prime number
{
flag = 0;
break;
}
}
return flag;
}
int checkArmstrongNumber(int n)
{
int originalNumber, remainder, result = 0, n = 0, flag;
originalNumber = number;
while (originalNumber != 0)
{
originalNumber /= 10;
++n;
}
originalNumber = number;
while (originalNumber != 0)
{
remainder = originalNumber%10;
result += pow(remainder, n);
originalNumber /= 10;
}

if(result == number)  // condition for Armstrong number
flag = 1;
else
flag = 0;
return flag;
}
int main()
{
int n, flag;
printf("Enter a positive integer: ");
scanf("%d", &n);

flag = checkPrimeNumber(n); // Check prime number
if (flag == 1)
printf("%d is a prime number.\n", n);
else
printf("%d is not a prime number.\n", n);

flag = checkArmstrongNumber(n);  // Check Armstrong number
if (flag == 1)
printf("%d is an Armstrong number.", n);
else
printf("%d is not an Armstrong number.",n);
return 0;
}``````
``````Output:

Enter a positive integer: 407
407 is not a prime number.
407 is an Armstrong number.``````