const partition = N => {
  for (let i = 1; i <= Math.sqrt(N); i++) {
    if (isPrime(i) && N % i == 0) {
      return [i, N / i];
    }
  }
};

const isPrime = n => {
  if (n <= 1) {
    return false;
  }

  for (let i = 2; i < n; i++) {
    if (n % i == 0) {
      return false;
    }
  }

  return true;
};

const gcd = (a, b) => {
  if (!b) {
    return a;
  }

  return gcd(b, a % b);
};

const e = 127;
const N = 1643;

const parts = partition(1643);
const phi = (parts[0] - 1) * (parts[1] - 1);

for (let i = 1; i <= phi; i++) {
  if ((i * e) % phi == 1) {
    console.log(i);
  }
}