function challenge19() { var n = prompt(" Enter two numbers:").split(" "), n1 = Number(n[0]), n2 = Number(n[1]), A = [], a = 0; if (Number.isNaN(n1) || Number.isNaN(n2) || n1 > n2 || !Number.isInteger(n1) || !Number.isInteger(n2) || n1 <= 0) { alert("Invalid Input!"); return; } for (var N = n1; N <= n2; N++) if(isPrime(N) && isPrime(toWords(N).length)) A[a++] = N; document.write(a + " such number(s) exist between " + n1 + " and " + n2 + ".

"); for (var u = 0; u < a; u++) document.write("" + A[u] + " (" + toWords(A[u]).toLowerCase() + " : Length " + toWords(A[u]).length + ")" + "
"); } function toWords(n) { var N = "", th = Math.floor(n / 1000), hu = Math.floor(n / 100) % 10, te = Math.floor(n) % 100; if (th > 0) N += toWord(th) + "THOUSAND"; if (hu > 0) N += toWord(hu) + "HUNDRED"; if ((te > 0) && (hu > 0 || th > 0)) N += "AND"; if (te > 0) N += toWord(te); return N; } function toWord(n) { var N = ""; if (n === 1) N += "ONE"; else if (n === 2) N += "TWO"; else if (n === 3) N += "THREE"; else if (n === 4) N += "FOUR"; else if (n === 5) N += "FIVE"; else if (n === 6) N += "SIX"; else if (n === 7) N += "SEVEN"; else if (n === 8) N += "EIGHT"; else if (n === 9) N += "NINE"; else if (n === 10) N += "TEN"; else if (n === 11) N += "ELEVEN"; else if (n === 12) N += "TWELVE"; else if (n === 13) N += "THIRTEEN"; else if (n === 14) N += "FOURTEEN"; else if (n === 15) N += "FIFTEEN"; else if (n === 16) N += "SIXTEEN"; else if (n === 17) N += "SEVENTEEN"; else if (n === 18) N += "EIGHTEEN"; else if (n === 19) N += "NINETEEN"; else if (n === 20) N += "TWENTY"; else if (n === 30) N += "THIRTY"; else if (n === 40) N += "FOURTY"; else if (n === 50) N += "FIFTY"; else if (n === 60) N += "SIXTY"; else if (n === 70) N += "SEVENTY"; else if (n === 80) N += "EIGHTY"; else if (n === 90) N += "NINETY"; else N += toWord(n - n % 10) + toWord(n % 10); return N; } function isPrime(n) { if (n === 1) return false; for (var N = 2; N < n; N++) if (Number.isInteger(n / N)) return false; return true; }

Challenge 19