18438361 has 2 divisors, whose sum is σ = 18438362. Its totient is φ = 18438360.

The previous prime is 18438359. The next prime is 18438373. The reversal of 18438361 is 16383481.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17172736 + 1265625 = 4144^2 + 1125^2 .

It is an emirp because it is prime and its reverse (16383481) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18438361 - 2¹ = 18438359 is a prime.

Together with 18438359, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (18438311) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9219180 + 9219181.

It is an arithmetic number, because the mean of its divisors is an integer number (9219181).

Almost surely, 2^18438361 is an apocalyptic number.

It is an amenable number.

18438361 is a deficient number, since it is larger than the sum of its proper divisors (1).

18438361 is an equidigital number, since it uses as much as digits as its factorization.

18438361 is an evil number, because the sum of its binary digits is even.

The product of its digits is 13824, while the sum is 34.

The square root of 18438361 is about 4293.9912668751. The cubic root of 18438361 is about 264.1845635104.

The spelling of 18438361 in words is "eighteen million, four hundred thirty-eight thousand, three hundred sixty-one".