21556800 has 168 divisors, whose sum is σ = 78740000. Its totient is φ = 5736960.

The previous prime is 21556783. The next prime is 21556841. The reversal of 21556800 is 865512.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 42951 + ... + 43449.

Almost surely, 2^21556800 is an apocalyptic number.

21556800 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 21556800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39370000).

21556800 is an abundant number, since it is smaller than the sum of its proper divisors (57183200).

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

21556800 is a wasteful number, since it uses less digits than its factorization.

21556800 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 530 (or 509 counting only the distinct ones).

The product of its (nonzero) digits is 2400, while the sum is 27.

The square root of 21556800 is about 4642.9301093167. The cubic root of 21556800 is about 278.3095425500.

The spelling of 21556800 in words is "twenty-one million, five hundred fifty-six thousand, eight hundred".