1991921811011 has 8 divisors (see below), whose sum is σ = 2173225870848. Its totient is φ = 1810654461000.

The previous prime is 1991921810987. The next prime is 1991921811049. The reversal of 1991921811011 is 1101181291991.

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

It is not a de Polignac number, because 1991921811011 - 2⁶ = 1991921810947 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1991921811071) 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, 9063935 + ... + 9281096.

It is an arithmetic number, because the mean of its divisors is an integer number (271653233856).

Almost surely, 2^{1991921811011} is an apocalyptic number.

1991921811011 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

1991921811011 is a deficient number, since it is larger than the sum of its proper divisors (181304059837).

1991921811011 is a wasteful number, since it uses less digits than its factorization.

1991921811011 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18354913.

The product of its (nonzero) digits is 11664, while the sum is 44.

The spelling of 1991921811011 in words is "one trillion, nine hundred ninety-one billion, nine hundred twenty-one million, eight hundred eleven thousand, eleven".