21956364928 has 64 divisors (see below), whose sum is σ = 45399261600. Its totient is φ = 10564549632.

The previous prime is 21956364923. The next prime is 21956364931. The reversal of 21956364928 is 82946365912.

It is a tau number, because it is divible by the number of its divisors (64).

It is not an unprimeable number, because it can be changed into a prime (21956364923) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1129951 + ... + 1149217.

Almost surely, 2^21956364928 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 21956364928, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22699630800).

21956364928 is an abundant number, since it is smaller than the sum of its proper divisors (23442896672).

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

21956364928 is a wasteful number, since it uses less digits than its factorization.

21956364928 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19617 (or 19605 counting only the distinct ones).

The product of its digits is 5598720, while the sum is 55.

It can be divided in two parts, 21956 and 364928, that added together give a square (386884 = 622²).

The spelling of 21956364928 in words is "twenty-one billion, nine hundred fifty-six million, three hundred sixty-four thousand, nine hundred twenty-eight".