21881804 has 12 divisors (see below), whose sum is σ = 43763664. Its totient is φ = 9377904.

The previous prime is 21881801. The next prime is 21881819. The reversal of 21881804 is 40818812.

21881804 is an admirable number.

It is not an unprimeable number, because it can be changed into a prime (21881801) 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, 390719 + ... + 390774.

It is an arithmetic number, because the mean of its divisors is an integer number (3646972).

Almost surely, 2^21881804 is an apocalyptic number.

It is an amenable number.

21881804 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

21881804 is a wasteful number, since it uses less digits than its factorization.

21881804 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 781504 (or 781502 counting only the distinct ones).

The product of its (nonzero) digits is 4096, while the sum is 32.

The square root of 21881804 is about 4677.7990551113. The cubic root of 21881804 is about 279.7012289319.

The spelling of 21881804 in words is "twenty-one million, eight hundred eighty-one thousand, eight hundred four".