18356771809 has 2 divisors, whose sum is σ = 18356771810. Its totient is φ = 18356771808.

The previous prime is 18356771801. The next prime is 18356771833. The reversal of 18356771809 is 90817765381.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18232560784 + 124211025 = 135028^2 + 11145^2 .

It is a cyclic number.

It is not a de Polignac number, because 18356771809 - 2³ = 18356771801 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 18356771809.

It is not a weakly prime, because it can be changed into another prime (18356771801) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9178385904 + 9178385905.

It is an arithmetic number, because the mean of its divisors is an integer number (9178385905).

Almost surely, 2^18356771809 is an apocalyptic number.

It is an amenable number.

18356771809 is a deficient number, since it is larger than the sum of its proper divisors (1).

18356771809 is an equidigital number, since it uses as much as digits as its factorization.

18356771809 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2540160, while the sum is 55.

The spelling of 18356771809 in words is "eighteen billion, three hundred fifty-six million, seven hundred seventy-one thousand, eight hundred nine".