21856843008 has 972 divisors, whose sum is σ = 88345097568. Its totient is φ = 5240401920.

The previous prime is 21856842967. The next prime is 21856843013. The reversal of 21856843008 is 80034865812.

21856843008 is a `hidden beast` number, since 218 + 56 + 84 + 300 + 8 = 666.

It is a tau number, because it is divible by the number of its divisors (972).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 107 ways as a sum of consecutive naturals, for example, 1681295610 + ... + 1681295622.

Almost surely, 2^21856843008 is an apocalyptic number.

21856843008 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21856843008, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (44172548784).

21856843008 is an abundant number, since it is smaller than the sum of its proper divisors (66488254560).

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

21856843008 is an frugal number, since it uses more digits than its factorization.

21856843008 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 84 (or 36 counting only the distinct ones).

The product of its (nonzero) digits is 368640, while the sum is 45.

The spelling of 21856843008 in words is "twenty-one billion, eight hundred fifty-six million, eight hundred forty-three thousand, eight".