18855436517 has 2 divisors, whose sum is σ = 18855436518. Its totient is φ = 18855436516.

The previous prime is 18855436513. The next prime is 18855436549. The reversal of 18855436517 is 71563455881.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18410690596 + 444745921 = 135686^2 + 21089^2 .

It is a cyclic number.

It is not a de Polignac number, because 18855436517 - 2² = 18855436513 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18855436513) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9427718258 + 9427718259.

It is an arithmetic number, because the mean of its divisors is an integer number (9427718259).

Almost surely, 2^18855436517 is an apocalyptic number.

It is an amenable number.

18855436517 is a deficient number, since it is larger than the sum of its proper divisors (1).

18855436517 is an equidigital number, since it uses as much as digits as its factorization.

18855436517 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4032000, while the sum is 53.

The spelling of 18855436517 in words is "eighteen billion, eight hundred fifty-five million, four hundred thirty-six thousand, five hundred seventeen".