18181818 has 48 divisors (see below), whose sum is σ = 40623336. Its totient is φ = 5875200.

The previous prime is 18181817. The next prime is 18181829. The reversal of 18181818 is 81818181.

It can be written as a sum of positive squares in 4 ways, for example, as 18173169 + 8649 = 4263^2 + 93^2 .

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

18181818 is an undulating number in base 10.

18181818 is a modest number, since divided by 181818 gives 18 as remainder.

It is not an unprimeable number, because it can be changed into a prime (18181817) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 132646 + ... + 132782.

Almost surely, 2^18181818 is an apocalyptic number.

18181818 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

18181818 is an abundant number, since it is smaller than the sum of its proper divisors (22441518).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

18181818 is a wasteful number, since it uses less digits than its factorization.

18181818 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 319 (or 316 counting only the distinct ones).

The product of its digits is 4096, while the sum is 36.

The square root of 18181818 is about 4264.0143057921. The cubic root of 18181818 is about 262.9535885564.

Adding to 18181818 its reverse (81818181), we get a palindrome (99999999).

The spelling of 18181818 in words is "eighteen million, one hundred eighty-one thousand, eight hundred eighteen".