21804444 has 24 divisors (see below), whose sum is σ = 56530320. Its totient is φ = 7268112.

The previous prime is 21804361. The next prime is 21804449. The reversal of 21804444 is 44440812.

It is a happy number.

21804444 is a `hidden beast` number, since 218 + 0 + 4 + 444 = 666.

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

21804444 is a modest number, since divided by 4444 gives 2180 as remainder.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21804449) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 100839 + ... + 101054.

It is an arithmetic number, because the mean of its divisors is an integer number (2355430).

Almost surely, 2^21804444 is an apocalyptic number.

It is an amenable number.

21804444 is an abundant number, since it is smaller than the sum of its proper divisors (34725876).

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

21804444 is a wasteful number, since it uses less digits than its factorization.

21804444 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 201906 (or 201898 counting only the distinct ones).

The product of its (nonzero) digits is 4096, while the sum is 27.

The square root of 21804444 is about 4669.5228878334. The cubic root of 21804444 is about 279.3712251190.

The spelling of 21804444 in words is "twenty-one million, eight hundred four thousand, four hundred forty-four".