21040444240 has 80 divisors (see below), whose sum is σ = 50917276800. Its totient is φ = 8075966976.

The previous prime is 21040444237. The next prime is 21040444259. The reversal of 21040444240 is 4244404012.

It is a tau number, because it is divible by the number of its divisors (80).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 350341 + ... + 405979.

It is an arithmetic number, because the mean of its divisors is an integer number (636465960).

Almost surely, 2^21040444240 is an apocalyptic number.

21040444240 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21040444240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25458638400).

21040444240 is an abundant number, since it is smaller than the sum of its proper divisors (29876832560).

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

21040444240 is a wasteful number, since it uses less digits than its factorization.

21040444240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 55844 (or 55838 counting only the distinct ones).

The product of its (nonzero) digits is 4096, while the sum is 25.

Adding to 21040444240 its reverse (4244404012), we get a palindrome (25284848252).

The spelling of 21040444240 in words is "twenty-one billion, forty million, four hundred forty-four thousand, two hundred forty".