21820204 has 24 divisors (see below), whose sum is σ = 43817760. Its totient is φ = 9313536.

The previous prime is 21820193. The next prime is 21820207. The reversal of 21820204 is 40202812.

It is a super-2 number, since 2×21820204² = 952242605203232, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21820207) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6084 + ... + 8980.

It is an arithmetic number, because the mean of its divisors is an integer number (1825740).

Almost surely, 2^21820204 is an apocalyptic number.

It is an amenable number.

21820204 is an abundant number, since it is smaller than the sum of its proper divisors (21997556).

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

21820204 is a wasteful number, since it uses less digits than its factorization.

21820204 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3177 (or 3175 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 19.

The square root of 21820204 is about 4671.2101215852. The cubic root of 21820204 is about 279.4385176726.

The spelling of 21820204 in words is "twenty-one million, eight hundred twenty thousand, two hundred four".