21855584256 has 120 divisors (see below), whose sum is σ = 63579513984. Its totient is φ = 6622740480.

The previous prime is 21855584249. The next prime is 21855584269. The reversal of 21855584256 is 65248555812.

It is a super-2 number, since 2×21855584256² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21855584199 and 21855584208.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 520461 + ... + 560883.

Almost surely, 2^21855584256 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21855584256, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31789756992).

21855584256 is an abundant number, since it is smaller than the sum of its proper divisors (41723929728).

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

21855584256 is an equidigital number, since it uses as much as digits as its factorization.

21855584256 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40465 (or 40439 counting only the distinct ones).

The product of its digits is 3840000, while the sum is 51.

The spelling of 21855584256 in words is "twenty-one billion, eight hundred fifty-five million, five hundred eighty-four thousand, two hundred fifty-six".