18656627081 has 4 divisors (see below), whose sum is σ = 18659909892. Its totient is φ = 18653344272.

The previous prime is 18656627071. The next prime is 18656627083. The reversal of 18656627081 is 18072665681.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 18072665681 = 7 ⋅2581809383.

It can be written as a sum of positive squares in 2 ways, for example, as 2849851456 + 15806775625 = 53384^2 + 125725^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18656627081 is a prime.

It is a super-2 number, since 2×18656627081² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18656627083) 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, 1632866 + ... + 1644251.

It is an arithmetic number, because the mean of its divisors is an integer number (4664977473).

Almost surely, 2^18656627081 is an apocalyptic number.

It is an amenable number.

18656627081 is a deficient number, since it is larger than the sum of its proper divisors (3282811).

18656627081 is an equidigital number, since it uses as much as digits as its factorization.

18656627081 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3282810.

The product of its (nonzero) digits is 967680, while the sum is 50.

The spelling of 18656627081 in words is "eighteen billion, six hundred fifty-six million, six hundred twenty-seven thousand, eighty-one".