21804788 has 12 divisors (see below), whose sum is σ = 38402532. Its totient is φ = 10832640.

The previous prime is 21804779. The next prime is 21804793. The reversal of 21804788 is 88740812.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 9498724 + 12306064 = 3082^2 + 3508^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16733 + ... + 17988.

It is an arithmetic number, because the mean of its divisors is an integer number (3200211).

Almost surely, 2^21804788 is an apocalyptic number.

It is an amenable number.

21804788 is a deficient number, since it is larger than the sum of its proper divisors (16597744).

21804788 is a wasteful number, since it uses less digits than its factorization.

21804788 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 34882 (or 34880 counting only the distinct ones).

The product of its (nonzero) digits is 28672, while the sum is 38.

The square root of 21804788 is about 4669.5597222865. The cubic root of 21804788 is about 279.3726942874.

The spelling of 21804788 in words is "twenty-one million, eight hundred four thousand, seven hundred eighty-eight".