21856800 has 144 divisors (see below), whose sum is σ = 81369792. Its totient is φ = 4992000.

The previous prime is 21856763. The next prime is 21856801. The reversal of 21856800 is 865812.

21856800 = T₃₂₅ + T₃₂₆ + ... + T₅₄₈.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is not an unprimeable number, because it can be changed into a prime (21856801) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 16150 + ... + 17450.

It is an arithmetic number, because the mean of its divisors is an integer number (565068).

Almost surely, 2^21856800 is an apocalyptic number.

21856800 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 21856800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (40684896).

21856800 is an abundant number, since it is smaller than the sum of its proper divisors (59512992).

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

21856800 is a wasteful number, since it uses less digits than its factorization.

21856800 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1331 (or 1318 counting only the distinct ones).

The product of its (nonzero) digits is 3840, while the sum is 30.

The square root of 21856800 is about 4675.1256667602. The cubic root of 21856800 is about 279.5946515664.

The spelling of 21856800 in words is "twenty-one million, eight hundred fifty-six thousand, eight hundred".