21808000 has 128 divisors (see below), whose sum is σ = 57283200. Its totient is φ = 8243200.

The previous prime is 21807959. The next prime is 21808013. The reversal of 21808000 is 80812.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (128).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 463977 + ... + 464023.

It is an arithmetic number, because the mean of its divisors is an integer number (447525).

Almost surely, 2^21808000 is an apocalyptic number.

21808000 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 21808000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28641600).

21808000 is an abundant number, since it is smaller than the sum of its proper divisors (35475200).

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

21808000 is an equidigital number, since it uses as much as digits as its factorization.

21808000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 105 (or 83 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 19.

The square root of 21808000 is about 4669.9036392628. The cubic root of 21808000 is about 279.3864114739.

Adding to 21808000 its reverse (80812), we get a palindrome (21888812).

The spelling of 21808000 in words is "twenty-one million, eight hundred eight thousand".