21943990865 has 8 divisors (see below), whose sum is σ = 26588447808. Its totient is φ = 17384753520.

The previous prime is 21943990843. The next prime is 21943990877. The reversal of 21943990865 is 56809934912.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21943990865 - 2¹⁰ = 21943989841 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21943990865.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 21304331 + ... + 21305360.

It is an arithmetic number, because the mean of its divisors is an integer number (3323555976).

Almost surely, 2^21943990865 is an apocalyptic number.

It is an amenable number.

21943990865 is a deficient number, since it is larger than the sum of its proper divisors (4644456943).

21943990865 is a wasteful number, since it uses less digits than its factorization.

21943990865 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42609799.

The product of its (nonzero) digits is 4199040, while the sum is 56.

The spelling of 21943990865 in words is "twenty-one billion, nine hundred forty-three million, nine hundred ninety thousand, eight hundred sixty-five".