21992565779 has 4 divisors (see below), whose sum is σ = 22010035320. Its totient is φ = 21975096240.

The previous prime is 21992565761. The next prime is 21992565821. The reversal of 21992565779 is 97756529912.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21992565779 - 2³² = 17697598483 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21992565719) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8732882 + ... + 8735399.

It is an arithmetic number, because the mean of its divisors is an integer number (5502508830).

Almost surely, 2^21992565779 is an apocalyptic number.

21992565779 is a deficient number, since it is larger than the sum of its proper divisors (17469541).

21992565779 is a wasteful number, since it uses less digits than its factorization.

21992565779 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17469540.

The product of its digits is 21432600, while the sum is 62.

The spelling of 21992565779 in words is "twenty-one billion, nine hundred ninety-two million, five hundred sixty-five thousand, seven hundred seventy-nine".