11991111111 has 24 divisors (see below), whose sum is σ = 20655498240. Its totient is φ = 6554146896.

The previous prime is 11991111103. The next prime is 11991111149. The reversal of 11991111111 is 11111119911.

It is not a de Polignac number, because 11991111111 - 2³ = 11991111103 is a prime.

It is a nude number because it is divisible by every one of its digits.

11991111111 is a modest number, since divided by 111111 gives 11991 as remainder.

It is a zygodrome in base 10.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (11991111161) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 4136271 + ... + 4139168.

It is an arithmetic number, because the mean of its divisors is an integer number (860645760).

Almost surely, 2^11991111111 is an apocalyptic number.

11991111111 is a deficient number, since it is larger than the sum of its proper divisors (8664387129).

11991111111 is a wasteful number, since it uses less digits than its factorization.

11991111111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8275475 (or 8275472 counting only the distinct ones).

The product of its digits is 81, while the sum is 27.

The spelling of 11991111111 in words is "eleven billion, nine hundred ninety-one million, one hundred eleven thousand, one hundred eleven".