181818181 has 4 divisors (see below), whose sum is σ = 182339500. Its totient is φ = 181296864.

The previous prime is 181818173. The next prime is 181818199.

181818181 is nontrivially palindromic in base 10.

181818181 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 71673156 + 110145025 = 8466^2 + 10495^2 .

It is a cyclic number.

It is not a de Polignac number, because 181818181 - 2³ = 181818173 is a prime.

It is a super-2 number, since 2×181818181² = 66115701884297522, which contains 22 as substring.

It is an alternating number because its digits alternate between odd and even.

181818181 is a strobogrammatic number because it is the same when read upside-down.

It is a Duffinian number.

181818181 is an undulating number in base 10.

It is a self number, because there is not a number n which added to its sum of digits gives 181818181.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (181818121) 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, 260136 + ... + 260833.

It is an arithmetic number, because the mean of its divisors is an integer number (45584875).

Almost surely, 2^181818181 is an apocalyptic number.

It is an amenable number.

181818181 is a deficient number, since it is larger than the sum of its proper divisors (521319).

181818181 is an equidigital number, since it uses as much as digits as its factorization.

181818181 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 521318.

The product of its digits is 4096, while the sum is 37.

The square root of 181818181 is about 13483.9972189258. The cubic root of 181818181 is about 566.5163340929.

It can be divided in two parts, 18181 and 8181, that added together give a palindrome (26362).

The spelling of 181818181 in words is "one hundred eighty-one million, eight hundred eighteen thousand, one hundred eighty-one".