21804442 has 16 divisors (see below), whose sum is σ = 35979264. Its totient is φ = 9909900.

The previous prime is 21804361. The next prime is 21804449. The reversal of 21804442 is 24440812.

It is not an unprimeable number, because it can be changed into a prime (21804449) 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, 1434 + ... + 6757.

It is an arithmetic number, because the mean of its divisors is an integer number (2248704).

Almost surely, 2^21804442 is an apocalyptic number.

21804442 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

21804442 is a deficient number, since it is larger than the sum of its proper divisors (14174822).

21804442 is an equidigital number, since it uses as much as digits as its factorization.

21804442 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8226 (or 8204 counting only the distinct ones).

The product of its (nonzero) digits is 2048, while the sum is 25.

The square root of 21804442 is about 4669.5226736788. The cubic root of 21804442 is about 279.3712165773.

The spelling of 21804442 in words is "twenty-one million, eight hundred four thousand, four hundred forty-two".