21564227663 has 4 divisors (see below), whose sum is σ = 23524612008. Its totient is φ = 19603843320.

The previous prime is 21564227651. The next prime is 21564227717. The reversal of 21564227663 is 36672246512.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21564227663 - 2⁸ = 21564227407 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21564227623) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 980192156 + ... + 980192177.

It is an arithmetic number, because the mean of its divisors is an integer number (5881153002).

Almost surely, 2^21564227663 is an apocalyptic number.

21564227663 is a deficient number, since it is larger than the sum of its proper divisors (1960384345).

21564227663 is a wasteful number, since it uses less digits than its factorization.

21564227663 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1960384344.

The product of its digits is 725760, while the sum is 44.

The spelling of 21564227663 in words is "twenty-one billion, five hundred sixty-four million, two hundred twenty-seven thousand, six hundred sixty-three".