18655855681 has 4 divisors (see below), whose sum is σ = 19007853012. Its totient is φ = 18303858352.

The previous prime is 18655855649. The next prime is 18655855721.

18655855681 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 12861601281 + 5794254400 = 113409^2 + 76120^2 .

It is a cyclic number.

It is not a de Polignac number, because 18655855681 - 2⁵ = 18655855649 is a prime.

It is a super-2 number, since 2×18655855681² (a number of 21 digits) contains 22 as substring.

It is a Smith number, since the sum of its digits (58) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18655855081) 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 in 3 ways as a sum of consecutive naturals, for example, 175998586 + ... + 175998691.

It is an arithmetic number, because the mean of its divisors is an integer number (4751963253).

Almost surely, 2^18655855681 is an apocalyptic number.

It is an amenable number.

18655855681 is a deficient number, since it is larger than the sum of its proper divisors (351997331).

18655855681 is an equidigital number, since it uses as much as digits as its factorization.

18655855681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 351997330.

The product of its digits is 11520000, while the sum is 58.

The spelling of 18655855681 in words is "eighteen billion, six hundred fifty-five million, eight hundred fifty-five thousand, six hundred eighty-one".