11891981691 has 12 divisors (see below), whose sum is σ = 17179695000. Its totient is φ = 7926885600.

The previous prime is 11891981681. The next prime is 11891981701. The reversal of 11891981691 is 19618919811.

It is an interprime number because it is at equal distance from previous prime (11891981681) and next prime (11891981701).

It is not a de Polignac number, because 11891981691 - 2¹⁵ = 11891948923 is a prime.

It is not an unprimeable number, because it can be changed into a prime (11891981681) 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 11 ways as a sum of consecutive naturals, for example, 20610 + ... + 155591.

It is an arithmetic number, because the mean of its divisors is an integer number (1431641250).

Almost surely, 2^11891981691 is an apocalyptic number.

11891981691 is a deficient number, since it is larger than the sum of its proper divisors (5287713309).

11891981691 is a wasteful number, since it uses less digits than its factorization.

11891981691 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 183706 (or 183703 counting only the distinct ones).

The product of its digits is 279936, while the sum is 54.

The spelling of 11891981691 in words is "eleven billion, eight hundred ninety-one million, nine hundred eighty-one thousand, six hundred ninety-one".