1991101111 has 8 divisors (see below), whose sum is σ = 2107662480. Its totient is φ = 1877733312.

The previous prime is 1991101103. The next prime is 1991101117. The reversal of 1991101111 is 1111011991.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1991101111 - 2³ = 1991101103 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1991101117) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 797110 + ... + 799603.

It is an arithmetic number, because the mean of its divisors is an integer number (263457810).

Almost surely, 2^1991101111 is an apocalyptic number.

1991101111 is a deficient number, since it is larger than the sum of its proper divisors (116561369).

1991101111 is a wasteful number, since it uses less digits than its factorization.

1991101111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1596785.

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

The square root of 1991101111 is about 44621.7560277495. The cubic root of 1991101111 is about 1258.0496219441.

The spelling of 1991101111 in words is "one billion, nine hundred ninety-one million, one hundred one thousand, one hundred eleven".