21856000 has 72 divisors (see below), whose sum is σ = 54525744. Its totient is φ = 8729600.

The previous prime is 21855983. The next prime is 21856031. The reversal of 21856000 is 65812.

It is a happy number.

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, 31659 + ... + 32341.

It is an arithmetic number, because the mean of its divisors is an integer number (757302).

Almost surely, 2^21856000 is an apocalyptic number.

21856000 is a gapful number since it is divisible by the number (20) 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 21856000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27262872).

21856000 is an abundant number, since it is smaller than the sum of its proper divisors (32669744).

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

21856000 is an frugal number, since it uses more digits than its factorization.

21856000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 714 (or 690 counting only the distinct ones).

The product of its (nonzero) digits is 480, while the sum is 22.

The square root of 21856000 is about 4675.0401067798. The cubic root of 21856000 is about 279.5912402947.

The spelling of 21856000 in words is "twenty-one million, eight hundred fifty-six thousand".