21800044 has 24 divisors (see below), whose sum is σ = 45497088. Its totient is φ = 8936400.

The previous prime is 21800039. The next prime is 21800047. The reversal of 21800044 is 44000812.

It is a junction number, because it is equal to n+sod(n) for n = 21799994 and 21800030.

It is not an unprimeable number, because it can be changed into a prime (21800047) by changing a digit.

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 in 7 ways as a sum of consecutive naturals, for example, 16282 + ... + 17569.

It is an arithmetic number, because the mean of its divisors is an integer number (1895712).

Almost surely, 2^21800044 is an apocalyptic number.

It is an amenable number.

21800044 is an abundant number, since it is smaller than the sum of its proper divisors (23697044).

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

21800044 is a wasteful number, since it uses less digits than its factorization.

21800044 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33885 (or 33883 counting only the distinct ones).

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

The square root of 21800044 is about 4669.0517238514. The cubic root of 21800044 is about 279.3524320680.

Adding to 21800044 its reverse (44000812), we get a palindrome (65800856).

The spelling of 21800044 in words is "twenty-one million, eight hundred thousand, forty-four".