21808804 has 6 divisors (see below), whose sum is σ = 38165414. Its totient is φ = 10904400.

The previous prime is 21808777. The next prime is 21808837. The reversal of 21808804 is 40880812.

It can be written as a sum of positive squares in only one way, i.e., 19980900 + 1827904 = 4470^2 + 1352^2 .

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 as a sum of consecutive naturals, namely, 2726097 + ... + 2726104.

Almost surely, 2^21808804 is an apocalyptic number.

It is an amenable number.

21808804 is a deficient number, since it is larger than the sum of its proper divisors (16356610).

21808804 is a wasteful number, since it uses less digits than its factorization.

21808804 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5452205 (or 5452203 counting only the distinct ones).

The product of its (nonzero) digits is 4096, while the sum is 31.

The square root of 21808804 is about 4669.9897216161. The cubic root of 21808804 is about 279.3898448304.

The spelling of 21808804 in words is "twenty-one million, eight hundred eight thousand, eight hundred four".