21660800 has 96 divisors (see below), whose sum is σ = 61216320. Its totient is φ = 7418880.

The previous prime is 21660791. The next prime is 21660827. The reversal of 21660800 is 806612.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 21917 + ... + 22883.

It is an arithmetic number, because the mean of its divisors is an integer number (637670).

Almost surely, 2^21660800 is an apocalyptic number.

21660800 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 21660800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30608160).

21660800 is an abundant number, since it is smaller than the sum of its proper divisors (39555520).

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

21660800 is an equidigital number, since it uses as much as digits as its factorization.

21660800 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 998 (or 981 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 23.

The square root of 21660800 is about 4654.1164575030. The cubic root of 21660800 is about 278.7563894853.

It can be divided in two parts, 216 and 60800, that added together give a palindrome (61016).

The spelling of 21660800 in words is "twenty-one million, six hundred sixty thousand, eight hundred".