111111009991 has 2 divisors, whose sum is σ = 111111009992. Its totient is φ = 111111009990.

The previous prime is 111111009959. The next prime is 111111010033. The reversal of 111111009991 is 199900111111.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 111111009991 - 2⁵ = 111111009959 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (111111009901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 55555504995 + 55555504996.

It is an arithmetic number, because the mean of its divisors is an integer number (55555504996).

Almost surely, 2^111111009991 is an apocalyptic number.

111111009991 is a deficient number, since it is larger than the sum of its proper divisors (1).

111111009991 is an equidigital number, since it uses as much as digits as its factorization.

111111009991 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 729, while the sum is 34.

The spelling of 111111009991 in words is "one hundred eleven billion, one hundred eleven million, nine thousand, nine hundred ninety-one".