16665181121 has 4 divisors (see below), whose sum is σ = 16676511744. Its totient is φ = 16653850500.

The previous prime is 16665181109. The next prime is 16665181129. The reversal of 16665181121 is 12118156661.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 16665181121 - 2¹⁰ = 16665180097 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (16665181129) 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, 5663105 + ... + 5666046.

It is an arithmetic number, because the mean of its divisors is an integer number (4169127936).

Almost surely, 2^16665181121 is an apocalyptic number.

It is an amenable number.

16665181121 is a deficient number, since it is larger than the sum of its proper divisors (11330623).

16665181121 is a wasteful number, since it uses less digits than its factorization.

16665181121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11330622.

The product of its digits is 17280, while the sum is 38.

The spelling of 16665181121 in words is "sixteen billion, six hundred sixty-five million, one hundred eighty-one thousand, one hundred twenty-one".