111111099991 has 2 divisors, whose sum is σ = 111111099992. Its totient is φ = 111111099990.

The previous prime is 111111099971. The next prime is 111111100007. The reversal of 111111099991 is 199990111111.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 111111099991 - 2¹¹ = 111111097943 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (111111099971) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 55555549995 + 55555549996.

It is an arithmetic number, because the mean of its divisors is an integer number (55555549996).

Almost surely, 2^111111099991 is an apocalyptic number.

111111099991 is a deficient number, since it is larger than the sum of its proper divisors (1).

111111099991 is an equidigital number, since it uses as much as digits as its factorization.

111111099991 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 6561, while the sum is 43.

The spelling of 111111099991 in words is "one hundred eleven billion, one hundred eleven million, ninety-nine thousand, nine hundred ninety-one".