21693820128 has 24 divisors (see below), whose sum is σ = 56946278088. Its totient is φ = 7231273344.

The previous prime is 21693820111. The next prime is 21693820147. The reversal of 21693820128 is 82102839612.

It is a tau number, because it is divible by the number of its divisors (24).

It is a self number, because there is not a number n which added to its sum of digits gives 21693820128.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 112988551 + ... + 112988742.

It is an arithmetic number, because the mean of its divisors is an integer number (2372761587).

Almost surely, 2^21693820128 is an apocalyptic number.

It is an amenable number.

21693820128 is an abundant number, since it is smaller than the sum of its proper divisors (35252457960).

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

21693820128 is a wasteful number, since it uses less digits than its factorization.

21693820128 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 225977306 (or 225977298 counting only the distinct ones).

The product of its (nonzero) digits is 82944, while the sum is 42.

The spelling of 21693820128 in words is "twenty-one billion, six hundred ninety-three million, eight hundred twenty thousand, one hundred twenty-eight".