18181818209 has 2 divisors, whose sum is σ = 18181818210. Its totient is φ = 18181818208.

The previous prime is 18181818119. The next prime is 18181818229. The reversal of 18181818209 is 90281818181.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 10803523600 + 7378294609 = 103940^2 + 85897^2 .

It is a cyclic number.

It is not a de Polignac number, because 18181818209 - 2¹² = 18181814113 is a prime.

It is not a weakly prime, because it can be changed into another prime (18181818229) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9090909104 + 9090909105.

It is an arithmetic number, because the mean of its divisors is an integer number (9090909105).

Almost surely, 2^18181818209 is an apocalyptic number.

It is an amenable number.

18181818209 is a deficient number, since it is larger than the sum of its proper divisors (1).

18181818209 is an equidigital number, since it uses as much as digits as its factorization.

18181818209 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 73728, while the sum is 47.

The spelling of 18181818209 in words is "eighteen billion, one hundred eighty-one million, eight hundred eighteen thousand, two hundred nine".