101111001991 has 2 divisors, whose sum is σ = 101111001992. Its totient is φ = 101111001990.

The previous prime is 101111001947. The next prime is 101111002049. The reversal of 101111001991 is 199100111101.

It is a weak prime.

It is an emirp because it is prime and its reverse (199100111101) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 101111001991 - 2¹⁷ = 101110870919 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (101111001931) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 50555500995 + 50555500996.

It is an arithmetic number, because the mean of its divisors is an integer number (50555500996).

Almost surely, 2^101111001991 is an apocalyptic number.

101111001991 is a deficient number, since it is larger than the sum of its proper divisors (1).

101111001991 is an equidigital number, since it uses as much as digits as its factorization.

101111001991 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 81, while the sum is 25.

The spelling of 101111001991 in words is "one hundred one billion, one hundred eleven million, one thousand, nine hundred ninety-one".