A number is twisted prime if it is a prime number and reverse of the number is also a prime number. for example. 11, 13, 17 etc.
function reverse( n:number) { let rev = 0, r=0; while (n > 0) { r = n % 10; rev = rev * 10 + r; n /= 10; } return rev; } function reverseNumber(num:number) { var n= num; var rev = 0, rem; while (n>0) { rem = n % 10; rev = rev * 10 + rem ; n = Math.floor(n/10); } return rev; } // Returns true if n is prime function isPrimeNumber( n:number ) { // return false is if value is one if (n <= 1) return false; if (n <= 3) // return true if value is 2 return true; // check the number is divided by 2 or 3 and return the false if (n % 2 == 0 || n % 3 == 0) return false; // for (var i = 5; i * i <= n; i = i + 6) if (n % i == 0 || n % (i + 2) == 0) return false; return true; } // let isPrimeNumberResult = isPrimeNumber(97); // console.log(isPrimeNumberResult); function isTwistedPrimeNumber(value:number ) : boolean { // first check passed number is prime or not. If not then return the false. if(isPrimeNumber(value) == false ) { return false ; } // reverse the number and check the reverse number is prime number or not if(isPrimeNumber(reverseNumber(value)) == true) { return true ; } else { return false ; } } // console all the two digit twisted prime numbers function printTwistedPrimeNumberOf2Digits(){ for (let index = 11; index <=99; index++) { if(isTwistedPrimeNumber(index)){ console.log(index); } } } printTwistedPrimeNumberOf2Digits();