191111988857 has 4 divisors (see below), whose sum is σ = 191565936996. Its totient is φ = 190658040720.

The previous prime is 191111988829. The next prime is 191111988869. The reversal of 191111988857 is 758889111191.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 758889111191 = 62927 ⋅12059833.

It can be written as a sum of positive squares in 2 ways, for example, as 9992801296 + 181119187561 = 99964^2 + 425581^2 .

It is a cyclic number.

It is not a de Polignac number, because 191111988857 - 2²⁰ = 191110940281 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 191111988796 and 191111988805.

It is not an unprimeable number, because it can be changed into a prime (191111988757) 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, 226973438 + ... + 226974279.

It is an arithmetic number, because the mean of its divisors is an integer number (47891484249).

Almost surely, 2^191111988857 is an apocalyptic number.

It is an amenable number.

191111988857 is a deficient number, since it is larger than the sum of its proper divisors (453948139).

191111988857 is an equidigital number, since it uses as much as digits as its factorization.

191111988857 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 453948138.

The product of its digits is 1451520, while the sum is 59.

The spelling of 191111988857 in words is "one hundred ninety-one billion, one hundred eleven million, nine hundred eighty-eight thousand, eight hundred fifty-seven".