11891208921 has 16 divisors (see below), whose sum is σ = 16038388800. Its totient is φ = 7835810048.

The previous prime is 11891208907. The next prime is 11891208971. The reversal of 11891208921 is 12980219811.

It is a happy number.

11891208921 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a cyclic number.

It is not a de Polignac number, because 11891208921 - 2⁷ = 11891208793 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (11891208971) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1131925 + ... + 1142381.

It is an arithmetic number, because the mean of its divisors is an integer number (1002399300).

Almost surely, 2^11891208921 is an apocalyptic number.

It is an amenable number.

11891208921 is a deficient number, since it is larger than the sum of its proper divisors (4147179879).

11891208921 is a wasteful number, since it uses less digits than its factorization.

11891208921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14808.

The product of its (nonzero) digits is 20736, while the sum is 42.

The spelling of 11891208921 in words is "eleven billion, eight hundred ninety-one million, two hundred eight thousand, nine hundred twenty-one".