21664423799 has 2 divisors, whose sum is σ = 21664423800. Its totient is φ = 21664423798.

The previous prime is 21664423793. The next prime is 21664423831. The reversal of 21664423799 is 99732446612.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21664423799 - 2⁴ = 21664423783 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21664423799.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21664423793) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10832211899 + 10832211900.

It is an arithmetic number, because the mean of its divisors is an integer number (10832211900).

Almost surely, 2^21664423799 is an apocalyptic number.

21664423799 is a deficient number, since it is larger than the sum of its proper divisors (1).

21664423799 is an equidigital number, since it uses as much as digits as its factorization.

21664423799 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3919104, while the sum is 53.

The spelling of 21664423799 in words is "twenty-one billion, six hundred sixty-four million, four hundred twenty-three thousand, seven hundred ninety-nine".