21221804 has 6 divisors (see below), whose sum is σ = 37138164. Its totient is φ = 10610900.

The previous prime is 21221791. The next prime is 21221821. The reversal of 21221804 is 40812212.

It is a happy number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2652722 + ... + 2652729.

It is an arithmetic number, because the mean of its divisors is an integer number (6189694).

Almost surely, 2^21221804 is an apocalyptic number.

It is an amenable number.

21221804 is a deficient number, since it is larger than the sum of its proper divisors (15916360).

21221804 is a wasteful number, since it uses less digits than its factorization.

21221804 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5305455 (or 5305453 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 20.

The square root of 21221804 is about 4606.7129278912. The cubic root of 21221804 is about 276.8603517873.

The spelling of 21221804 in words is "twenty-one million, two hundred twenty-one thousand, eight hundred four".