1001991111 has 16 divisors (see below), whose sum is σ = 1470817920. Its totient is φ = 601693920.

The previous prime is 1001991077. The next prime is 1001991127. The reversal of 1001991111 is 1111991001.

It is not a de Polignac number, because 1001991111 - 2¹⁸ = 1001728967 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1001991161) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 135685 + ... + 142878.

It is an arithmetic number, because the mean of its divisors is an integer number (91926120).

Almost surely, 2^1001991111 is an apocalyptic number.

1001991111 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

1001991111 is a deficient number, since it is larger than the sum of its proper divisors (468826809).

1001991111 is a wasteful number, since it uses less digits than its factorization.

1001991111 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 278686.

The product of its (nonzero) digits is 81, while the sum is 24.

The square root of 1001991111 is about 31654.2431752838. The cubic root of 1001991111 is about 1000.6632636507.

The spelling of 1001991111 in words is "one billion, one million, nine hundred ninety-one thousand, one hundred eleven".