1818181818181 has 4 divisors (see below), whose sum is σ = 1818189449100. Its totient is φ = 1818174187264.

The previous prime is 1818181818179. The next prime is 1818181818227.

It is a happy number.

1818181818181 is nontrivially palindromic in base 10.

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 253043205156 + 1565138613025 = 503034^2 + 1251055^2 .

It is a cyclic number.

It is not a de Polignac number, because 1818181818181 - 2¹ = 1818181818179 is a prime.

It is a super-2 number, since 2×1818181818181² (a number of 25 digits) contains 22 as substring.

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

1818181818181 is a strobogrammatic number because it is the same when read upside-down.

It is a Duffinian number.

1818181818181 is an undulating number in base 10.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1818181815181) 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, 3446146 + ... + 3938563.

It is an arithmetic number, because the mean of its divisors is an integer number (454547362275).

Almost surely, 2^{1818181818181} is an apocalyptic number.

It is an amenable number.

1818181818181 is a deficient number, since it is larger than the sum of its proper divisors (7630919).

1818181818181 is an equidigital number, since it uses as much as digits as its factorization.

1818181818181 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7630918.

The product of its digits is 262144, while the sum is 55.

It can be divided in two parts, 1818181 and 818181, that added together give a palindrome (2636362).

The spelling of 1818181818181 in words is "one trillion, eight hundred eighteen billion, one hundred eighty-one million, eight hundred eighteen thousand, one hundred eighty-one".