21905026561 has 8 divisors (see below), whose sum is σ = 24223741344. Its totient is φ = 19640869920.

The previous prime is 21905026523. The next prime is 21905026579. The reversal of 21905026561 is 16562050912.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21905026561 - 2²⁷ = 21770808833 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21905026561.

It is not an unprimeable number, because it can be changed into a prime (21905026501) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 13638691 + ... + 13640296.

It is an arithmetic number, because the mean of its divisors is an integer number (3027967668).

Almost surely, 2^21905026561 is an apocalyptic number.

It is an amenable number.

21905026561 is a deficient number, since it is larger than the sum of its proper divisors (2318714783).

21905026561 is a wasteful number, since it uses less digits than its factorization.

21905026561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27279071.

The product of its (nonzero) digits is 32400, while the sum is 37.

The spelling of 21905026561 in words is "twenty-one billion, nine hundred five million, twenty-six thousand, five hundred sixty-one".