18193686857 has 4 divisors (see below), whose sum is σ = 18194169876. Its totient is φ = 18193203840.

The previous prime is 18193686839. The next prime is 18193687007. The reversal of 18193686857 is 75868639181.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 75868639181 = 4909 ⋅15455009.

It can be written as a sum of positive squares in 2 ways, for example, as 11703128761 + 6490558096 = 108181^2 + 80564^2 .

It is a cyclic number.

It is not a de Polignac number, because 18193686857 - 2¹⁶ = 18193621321 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 18193686857.

It is not an unprimeable number, because it can be changed into a prime (18193686827) 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, 179744 + ... + 262097.

It is an arithmetic number, because the mean of its divisors is an integer number (4548542469).

Almost surely, 2^18193686857 is an apocalyptic number.

It is an amenable number.

18193686857 is a deficient number, since it is larger than the sum of its proper divisors (483019).

18193686857 is an equidigital number, since it uses as much as digits as its factorization.

18193686857 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 483018.

The product of its digits is 17418240, while the sum is 62.

The spelling of 18193686857 in words is "eighteen billion, one hundred ninety-three million, six hundred eighty-six thousand, eight hundred fifty-seven".