2981991891 has 8 divisors (see below), whose sum is σ = 3976486864. Its totient is φ = 1987745760.

The previous prime is 2981991889. The next prime is 2981991899. The reversal of 2981991891 is 1981991892.

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

It is not a de Polignac number, because 2981991891 - 2¹ = 2981991889 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2981991899) 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 7 ways as a sum of consecutive naturals, for example, 32176 + ... + 83661.

It is an arithmetic number, because the mean of its divisors is an integer number (497060858).

Almost surely, 2^2981991891 is an apocalyptic number.

2981991891 is a deficient number, since it is larger than the sum of its proper divisors (994494973).

2981991891 is a wasteful number, since it uses less digits than its factorization.

2981991891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 124421.

The product of its digits is 839808, while the sum is 57.

The square root of 2981991891 is about 54607.6175180716. The cubic root of 2981991891 is about 1439.3579781692.

Subtracting from 2981991891 its reverse (1981991892), we obtain a palindrome (999999999).

The spelling of 2981991891 in words is "two billion, nine hundred eighty-one million, nine hundred ninety-one thousand, eight hundred ninety-one".