2018391991 has 16 divisors (see below), whose sum is σ = 2524071168. Its totient is φ = 1568001600.

The previous prime is 2018391961. The next prime is 2018392001. The reversal of 2018391991 is 1991938102.

It is a de Polignac number, because none of the positive numbers 2^k-2018391991 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 (2018391901) 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, 14110 + ... + 65083.

It is an arithmetic number, because the mean of its divisors is an integer number (157754448).

Almost surely, 2^2018391991 is an apocalyptic number.

2018391991 is a deficient number, since it is larger than the sum of its proper divisors (505679177).

2018391991 is a wasteful number, since it uses less digits than its factorization.

2018391991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 79542.

The product of its (nonzero) digits is 34992, while the sum is 43.

The square root of 2018391991 is about 44926.5176816543. The cubic root of 2018391991 is about 1263.7713475653.

The spelling of 2018391991 in words is "two billion, eighteen million, three hundred ninety-one thousand, nine hundred ninety-one".