18081691 has 2 divisors, whose sum is σ = 18081692. Its totient is φ = 18081690.

The previous prime is 18081689. The next prime is 18081733. The reversal of 18081691 is 19618081.

It is a weak prime. It is also a bemirp because it and its reverse can be mirrored producing other two distinct primes, 16918081 and 18081961.

It is a cyclic number.

It is not a de Polignac number, because 18081691 - 2¹ = 18081689 is a prime.

Together with 18081689, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (18081601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9040845 + 9040846.

It is an arithmetic number, because the mean of its divisors is an integer number (9040846).

Almost surely, 2^18081691 is an apocalyptic number.

18081691 is a deficient number, since it is larger than the sum of its proper divisors (1).

18081691 is an equidigital number, since it uses as much as digits as its factorization.

18081691 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3456, while the sum is 34.

The square root of 18081691 is about 4252.2571653182. The cubic root of 18081691 is about 262.4700059456.

The spelling of 18081691 in words is "eighteen million, eighty-one thousand, six hundred ninety-one".