18391361 has 2 divisors, whose sum is σ = 18391362. Its totient is φ = 18391360.

The previous prime is 18391357. The next prime is 18391363. The reversal of 18391361 is 16319381.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17901361 + 490000 = 4231^2 + 700^2 .

It is a cyclic number.

It is not a de Polignac number, because 18391361 - 2² = 18391357 is a prime.

It is a Sophie Germain prime.

Together with 18391363, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (18391363) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9195680 + 9195681.

It is an arithmetic number, because the mean of its divisors is an integer number (9195681).

Almost surely, 2^18391361 is an apocalyptic number.

It is an amenable number.

18391361 is a deficient number, since it is larger than the sum of its proper divisors (1).

18391361 is an equidigital number, since it uses as much as digits as its factorization.

18391361 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3888, while the sum is 32.

The square root of 18391361 is about 4288.5150110499. The cubic root of 18391361 is about 263.9599007431.

The spelling of 18391361 in words is "eighteen million, three hundred ninety-one thousand, three hundred sixty-one".