21385844 has 12 divisors (see below), whose sum is σ = 37465764. Its totient is φ = 10681344.

The previous prime is 21385843. The next prime is 21385867. The reversal of 21385844 is 44858312.

It can be written as a sum of positive squares in 2 ways, for example, as 11222500 + 10163344 = 3350^2 + 3188^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21385843) 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 3 ways as a sum of consecutive naturals, for example, 2294 + ... + 6930.

It is an arithmetic number, because the mean of its divisors is an integer number (3122147).

Almost surely, 2^21385844 is an apocalyptic number.

It is an amenable number.

21385844 is a deficient number, since it is larger than the sum of its proper divisors (16079920).

21385844 is a wasteful number, since it uses less digits than its factorization.

21385844 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5794 (or 5792 counting only the distinct ones).

The product of its digits is 30720, while the sum is 35.

The square root of 21385844 is about 4624.4831062509. The cubic root of 21385844 is about 277.5718786829.

The spelling of 21385844 in words is "twenty-one million, three hundred eighty-five thousand, eight hundred forty-four".