18508181 has 2 divisors, whose sum is σ = 18508182. Its totient is φ = 18508180.

The previous prime is 18508159. The next prime is 18508187. The reversal of 18508181 is 18180581.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16273156 + 2235025 = 4034^2 + 1495^2 .

It is a cyclic number.

It is not a de Polignac number, because 18508181 - 2⁶ = 18508117 is a prime.

It is a super-2 number, since 2×18508181² = 685105527857522, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18508187) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9254090 + 9254091.

It is an arithmetic number, because the mean of its divisors is an integer number (9254091).

Almost surely, 2^18508181 is an apocalyptic number.

It is an amenable number.

18508181 is a deficient number, since it is larger than the sum of its proper divisors (1).

18508181 is an equidigital number, since it uses as much as digits as its factorization.

18508181 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2560, while the sum is 32.

The square root of 18508181 is about 4302.1135503378. The cubic root of 18508181 is about 264.5176034682.

The spelling of 18508181 in words is "eighteen million, five hundred eight thousand, one hundred eighty-one".