21563266544 has 40 divisors (see below), whose sum is σ = 43785843360. Its totient is φ = 10267792128.

The previous prime is 21563266493. The next prime is 21563266561. The reversal of 21563266544 is 44566236512.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 21563266495 and 21563266504.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 43667 + ... + 212210.

It is an arithmetic number, because the mean of its divisors is an integer number (1094646084).

Almost surely, 2^21563266544 is an apocalyptic number.

It is an amenable number.

21563266544 is an abundant number, since it is smaller than the sum of its proper divisors (22222576816).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21563266544 is a wasteful number, since it uses less digits than its factorization.

21563266544 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 256137 (or 256131 counting only the distinct ones).

The product of its digits is 1036800, while the sum is 44.

The spelling of 21563266544 in words is "twenty-one billion, five hundred sixty-three million, two hundred sixty-six thousand, five hundred forty-four".