21438044256 has 96 divisors (see below), whose sum is σ = 56935726848. Its totient is φ = 7062382080.

The previous prime is 21438044233. The next prime is 21438044323. The reversal of 21438044256 is 65244083412.

It is a tau number, because it is divible by the number of its divisors (96).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5644150 + ... + 5647946.

It is an arithmetic number, because the mean of its divisors is an integer number (593080488).

Almost surely, 2^21438044256 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21438044256, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28467863424).

21438044256 is an abundant number, since it is smaller than the sum of its proper divisors (35497682592).

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

21438044256 is a wasteful number, since it uses less digits than its factorization.

21438044256 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4484 (or 4476 counting only the distinct ones).

The product of its (nonzero) digits is 184320, while the sum is 39.

The spelling of 21438044256 in words is "twenty-one billion, four hundred thirty-eight million, forty-four thousand, two hundred fifty-six".