11681920891 has 4 divisors (see below), whose sum is σ = 11682327384. Its totient is φ = 11681514400.

The previous prime is 11681920871. The next prime is 11681920907. The reversal of 11681920891 is 19802918611.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-11681920891 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (11681920801) 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, 156565 + ... + 218806.

It is an arithmetic number, because the mean of its divisors is an integer number (2920581846).

Almost surely, 2^11681920891 is an apocalyptic number.

11681920891 is a deficient number, since it is larger than the sum of its proper divisors (406493).

11681920891 is an equidigital number, since it uses as much as digits as its factorization.

11681920891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 406492.

The product of its (nonzero) digits is 62208, while the sum is 46.

The spelling of 11681920891 in words is "eleven billion, six hundred eighty-one million, nine hundred twenty thousand, eight hundred ninety-one".