21564085903 has 2 divisors, whose sum is σ = 21564085904. Its totient is φ = 21564085902.

The previous prime is 21564085889. The next prime is 21564085937. The reversal of 21564085903 is 30958046512.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21564085903 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21564085903.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21564085973) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10782042951 + 10782042952.

It is an arithmetic number, because the mean of its divisors is an integer number (10782042952).

Almost surely, 2^21564085903 is an apocalyptic number.

21564085903 is a deficient number, since it is larger than the sum of its proper divisors (1).

21564085903 is an equidigital number, since it uses as much as digits as its factorization.

21564085903 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 259200, while the sum is 43.

The spelling of 21564085903 in words is "twenty-one billion, five hundred sixty-four million, eighty-five thousand, nine hundred three".