18090181 has 2 divisors, whose sum is σ = 18090182. Its totient is φ = 18090180.

The previous prime is 18090173. The next prime is 18090197. The reversal of 18090181 is 18109081.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14130081 + 3960100 = 3759^2 + 1990^2 .

It is an emirp because it is prime and its reverse (18109081) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18090181 - 2³ = 18090173 is a prime.

It is a super-2 number, since 2×18090181² = 654509297225522, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18096181) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9045090 + 9045091.

It is an arithmetic number, because the mean of its divisors is an integer number (9045091).

Almost surely, 2^18090181 is an apocalyptic number.

It is an amenable number.

18090181 is a deficient number, since it is larger than the sum of its proper divisors (1).

18090181 is an equidigital number, since it uses as much as digits as its factorization.

18090181 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 576, while the sum is 28.

The square root of 18090181 is about 4253.2553415002. The cubic root of 18090181 is about 262.5110791998.

The spelling of 18090181 in words is "eighteen million, ninety thousand, one hundred eighty-one".