18087691 has 2 divisors, whose sum is σ = 18087692. Its totient is φ = 18087690.

The previous prime is 18087679. The next prime is 18087697. The reversal of 18087691 is 19678081.

It is a strong prime.

It is an emirp because it is prime and its reverse (19678081) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18087691 - 2¹⁷ = 17956619 is a prime.

It is a super-2 number, since 2×18087691² = 654329131422962, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (18087697) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9043845 + 9043846.

It is an arithmetic number, because the mean of its divisors is an integer number (9043846).

Almost surely, 2^18087691 is an apocalyptic number.

18087691 is a deficient number, since it is larger than the sum of its proper divisors (1).

18087691 is an equidigital number, since it uses as much as digits as its factorization.

18087691 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 24192, while the sum is 40.

The square root of 18087691 is about 4252.9626144607. The cubic root of 18087691 is about 262.4990343124.

The spelling of 18087691 in words is "eighteen million, eighty-seven thousand, six hundred ninety-one".