21804128 has 24 divisors (see below), whose sum is σ = 43976520. Its totient is φ = 10635520.

The previous prime is 21804121. The next prime is 21804131. The reversal of 21804128 is 82140812.

It is a junction number, because it is equal to n+sod(n) for n = 21804097 and 21804106.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21804121) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6998 + ... + 9621.

It is an arithmetic number, because the mean of its divisors is an integer number (1832355).

Almost surely, 2^21804128 is an apocalyptic number.

It is an amenable number.

21804128 is an abundant number, since it is smaller than the sum of its proper divisors (22172392).

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

21804128 is a wasteful number, since it uses less digits than its factorization.

21804128 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16670 (or 16662 counting only the distinct ones).

The product of its (nonzero) digits is 1024, while the sum is 26.

The square root of 21804128 is about 4669.4890512775. The cubic root of 21804128 is about 279.3698755205.

The spelling of 21804128 in words is "twenty-one million, eight hundred four thousand, one hundred twenty-eight".