21820800 has 96 divisors (see below), whose sum is σ = 71903880. Its totient is φ = 5816320.

The previous prime is 21820793. The next prime is 21820811. The reversal of 21820800 is 802812.

It is a tau number, because it is divible by the number of its divisors (96).

It is a super-2 number, since 2×21820800² = 952294625280000, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 8464 + ... + 10736.

Almost surely, 2^21820800 is an apocalyptic number.

21820800 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 21820800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35951940).

21820800 is an abundant number, since it is smaller than the sum of its proper divisors (50083080).

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

21820800 is a wasteful number, since it uses less digits than its factorization.

21820800 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2300 (or 2283 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 21.

The square root of 21820800 is about 4671.2739161818. The cubic root of 21820800 is about 279.4410618566.

The spelling of 21820800 in words is "twenty-one million, eight hundred twenty thousand, eight hundred".