21665927918 has 8 divisors (see below), whose sum is σ = 33911887248. Its totient is φ = 10361965504.

The previous prime is 21665927911. The next prime is 21665927923. The reversal of 21665927918 is 81972956612.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21665927911) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 235499171 + ... + 235499262.

It is an arithmetic number, because the mean of its divisors is an integer number (4238985906).

Almost surely, 2^21665927918 is an apocalyptic number.

21665927918 is a deficient number, since it is larger than the sum of its proper divisors (12245959330).

21665927918 is a wasteful number, since it uses less digits than its factorization.

21665927918 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 470998458.

The product of its digits is 3265920, while the sum is 56.

The spelling of 21665927918 in words is "twenty-one billion, six hundred sixty-five million, nine hundred twenty-seven thousand, nine hundred eighteen".