18690181 has 4 divisors (see below), whose sum is σ = 19334700. Its totient is φ = 18045664.

The previous prime is 18690173. The next prime is 18690211. The reversal of 18690181 is 18109681.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 14945956 + 3744225 = 3866^2 + 1935^2 .

It is a cyclic number.

It is not a de Polignac number, because 18690181 - 2³ = 18690173 is a prime.

It is a super-2 number, since 2×18690181² = 698645731625522, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18691181) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 322216 + ... + 322273.

It is an arithmetic number, because the mean of its divisors is an integer number (4833675).

Almost surely, 2^18690181 is an apocalyptic number.

It is an amenable number.

18690181 is a deficient number, since it is larger than the sum of its proper divisors (644519).

18690181 is an equidigital number, since it uses as much as digits as its factorization.

18690181 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 644518.

The product of its (nonzero) digits is 3456, while the sum is 34.

The square root of 18690181 is about 4323.2141977931. The cubic root of 18690181 is about 265.3818205469.

The spelling of 18690181 in words is "eighteen million, six hundred ninety thousand, one hundred eighty-one".