21856091904 has 108 divisors (see below), whose sum is σ = 64357596576. Its totient is φ = 7130320896.

The previous prime is 21856091897. The next prime is 21856091911. The reversal of 21856091904 is 40919065812.

21856091904 is a `hidden beast` number, since 21 + 8 + 5 + 609 + 19 + 0 + 4 = 666.

It is an interprime number because it is at equal distance from previous prime (21856091897) and next prime (21856091911).

It is a self number, because there is not a number n which added to its sum of digits gives 21856091904.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 7372 + ... + 209204.

It is an arithmetic number, because the mean of its divisors is an integer number (595903672).

Almost surely, 2^21856091904 is an apocalyptic number.

21856091904 is a gapful number since it is divisible by the number (24) 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 21856091904, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32178798288).

21856091904 is an abundant number, since it is smaller than the sum of its proper divisors (42501504672).

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

21856091904 is a wasteful number, since it uses less digits than its factorization.

21856091904 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 201902 (or 201885 counting only the distinct ones).

The product of its (nonzero) digits is 155520, while the sum is 45.

The spelling of 21856091904 in words is "twenty-one billion, eight hundred fifty-six million, ninety-one thousand, nine hundred four".