18999991111 has 4 divisors (see below), whose sum is σ = 19060694272. Its totient is φ = 18939287952.

The previous prime is 18999991091. The next prime is 18999991117. The reversal of 18999991111 is 11119999981.

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

It is a cyclic number.

It is not a de Polignac number, because 18999991111 - 2⁵ = 18999991079 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18999991117) 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, 30351111 + ... + 30351736.

It is an arithmetic number, because the mean of its divisors is an integer number (4765173568).

Almost surely, 2^18999991111 is an apocalyptic number.

18999991111 is a deficient number, since it is larger than the sum of its proper divisors (60703161).

18999991111 is an equidigital number, since it uses as much as digits as its factorization.

18999991111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 60703160.

The product of its digits is 472392, while the sum is 58.

The spelling of 18999991111 in words is "eighteen billion, nine hundred ninety-nine million, nine hundred ninety-one thousand, one hundred eleven".