18163636181 has 4 divisors (see below), whose sum is σ = 18164336364. Its totient is φ = 18162936000.

The previous prime is 18163636177. The next prime is 18163636187.

18163636181 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 2153795281 + 16009840900 = 46409^2 + 126530^2 .

It is a cyclic number.

It is not a de Polignac number, because 18163636181 - 2² = 18163636177 is a prime.

It is a super-2 number, since 2×18163636181² (a number of 21 digits) contains 22 as substring.

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

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18163636187) 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, 309620 + ... + 363581.

It is an arithmetic number, because the mean of its divisors is an integer number (4541084091).

Almost surely, 2^18163636181 is an apocalyptic number.

It is an amenable number.

18163636181 is a deficient number, since it is larger than the sum of its proper divisors (700183).

18163636181 is an equidigital number, since it uses as much as digits as its factorization.

18163636181 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 700182.

The product of its digits is 124416, while the sum is 44.

The spelling of 18163636181 in words is "eighteen billion, one hundred sixty-three million, six hundred thirty-six thousand, one hundred eighty-one".