18555850861 has 2 divisors, whose sum is σ = 18555850862. Its totient is φ = 18555850860.

The previous prime is 18555850811. The next prime is 18555850909. The reversal of 18555850861 is 16805855581.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12875213961 + 5680636900 = 113469^2 + 75370^2 .

It is a cyclic number.

It is not a de Polignac number, because 18555850861 - 2¹⁵ = 18555818093 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 18555850799 and 18555850808.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18555850811) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9277925430 + 9277925431.

It is an arithmetic number, because the mean of its divisors is an integer number (9277925431).

Almost surely, 2^18555850861 is an apocalyptic number.

It is an amenable number.

18555850861 is a deficient number, since it is larger than the sum of its proper divisors (1).

18555850861 is an equidigital number, since it uses as much as digits as its factorization.

18555850861 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1920000, while the sum is 52.

The spelling of 18555850861 in words is "eighteen billion, five hundred fifty-five million, eight hundred fifty thousand, eight hundred sixty-one".