811111111 has 4 divisors (see below), whose sum is σ = 813977512. Its totient is φ = 808244712.

The previous prime is 811111079. The next prime is 811111129. The reversal of 811111111 is 111111118.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 111111118 = 2 ⋅55555559.

It is a cyclic number.

It is not a de Polignac number, because 811111111 - 2⁵ = 811111079 is a prime.

It is a Duffinian number.

811111111 is a modest number, since divided by 11111 gives 8111 as remainder.

It is a nialpdrome in base 10.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (811111181) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1432776 + ... + 1433341.

It is an arithmetic number, because the mean of its divisors is an integer number (203494378).

Almost surely, 2^811111111 is an apocalyptic number.

811111111 is a deficient number, since it is larger than the sum of its proper divisors (2866401).

811111111 is a wasteful number, since it uses less digits than its factorization.

811111111 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2866400.

The product of its digits is 8, while the sum is 16.

The square root of 811111111 is about 28480.0124824411. The cubic root of 811111111 is about 932.5957891666.

Adding to 811111111 its reverse (111111118), we get a palindrome (922222229).

It can be divided in two parts, 8 and 11111111, that multiplied together give a palindrome (88888888).

The spelling of 811111111 in words is "eight hundred eleven million, one hundred eleven thousand, one hundred eleven".