16564635247021 has 2 divisors, whose sum is σ = 16564635247022. Its totient is φ = 16564635247020.

The previous prime is 16564635247001. The next prime is 16564635247031. The reversal of 16564635247021 is 12074253646561.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15470966889225 + 1093668357796 = 3933315^2 + 1045786^2 .

It is an emirp because it is prime and its reverse (12074253646561) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-16564635247021 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 16564635247021.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (16564635247001) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8282317623510 + 8282317623511.

It is an arithmetic number, because the mean of its divisors is an integer number (8282317623511).

Almost surely, 2^{16564635247021} is an apocalyptic number.

It is an amenable number.

16564635247021 is a deficient number, since it is larger than the sum of its proper divisors (1).

16564635247021 is an equidigital number, since it uses as much as digits as its factorization.

16564635247021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 7257600, while the sum is 52.

The spelling of 16564635247021 in words is "sixteen trillion, five hundred sixty-four billion, six hundred thirty-five million, two hundred forty-seven thousand, twenty-one".