1891992981991 has 24 divisors (see below), whose sum is σ = 2297201523840. Its totient is φ = 1526148147072.

The previous prime is 1891992981953. The next prime is 1891992982001. The reversal of 1891992981991 is 1991892991981.

It is a happy number.

It is not a de Polignac number, because 1891992981991 - 2²⁵ = 1891959427559 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 (1891992981191) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 20708376 + ... + 20799538.

It is an arithmetic number, because the mean of its divisors is an integer number (95716730160).

Almost surely, 2^{1891992981991} is an apocalyptic number.

1891992981991 is a deficient number, since it is larger than the sum of its proper divisors (405208541849).

1891992981991 is a wasteful number, since it uses less digits than its factorization.

1891992981991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 101463 (or 101446 counting only the distinct ones).

The product of its digits is 68024448, while the sum is 76.

The spelling of 1891992981991 in words is "one trillion, eight hundred ninety-one billion, nine hundred ninety-two million, nine hundred eighty-one thousand, nine hundred ninety-one".