21668619994559 has 2 divisors, whose sum is σ = 21668619994560. Its totient is φ = 21668619994558.

The previous prime is 21668619994523. The next prime is 21668619994597. The reversal of 21668619994559 is 95549991686612.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21668619994559 - 2¹² = 21668619990463 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21668019994559) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10834309997279 + 10834309997280.

It is an arithmetic number, because the mean of its divisors is an integer number (10834309997280).

Almost surely, 2^{21668619994559} is an apocalyptic number.

21668619994559 is a deficient number, since it is larger than the sum of its proper divisors (1).

21668619994559 is an equidigital number, since it uses as much as digits as its factorization.

21668619994559 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2267481600, while the sum is 80.

The spelling of 21668619994559 in words is "twenty-one trillion, six hundred sixty-eight billion, six hundred nineteen million, nine hundred ninety-four thousand, five hundred fifty-nine".