18338581 has 2 divisors, whose sum is σ = 18338582. Its totient is φ = 18338580.

The previous prime is 18338561. The next prime is 18338587. The reversal of 18338581 is 18583381.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15563025 + 2775556 = 3945^2 + 1666^2 .

It is a cyclic number.

It is not a de Polignac number, because 18338581 - 2¹⁵ = 18305813 is a prime.

It is a super-2 number, since 2×18338581² = 672607106187122, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 18338581.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18338587) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9169290 + 9169291.

It is an arithmetic number, because the mean of its divisors is an integer number (9169291).

Almost surely, 2^18338581 is an apocalyptic number.

It is an amenable number.

18338581 is a deficient number, since it is larger than the sum of its proper divisors (1).

18338581 is an equidigital number, since it uses as much as digits as its factorization.

18338581 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 23040, while the sum is 37.

The square root of 18338581 is about 4282.3569444875. The cubic root of 18338581 is about 263.7071525074.

The spelling of 18338581 in words is "eighteen million, three hundred thirty-eight thousand, five hundred eighty-one".