18000181861 has 2 divisors, whose sum is σ = 18000181862. Its totient is φ = 18000181860.

The previous prime is 18000181831. The next prime is 18000181897. The reversal of 18000181861 is 16818100081.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15185879361 + 2814302500 = 123231^2 + 53050^2 .

It is a cyclic number.

It is not a de Polignac number, because 18000181861 - 2¹⁹ = 17999657573 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18000181831) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9000090930 + 9000090931.

It is an arithmetic number, because the mean of its divisors is an integer number (9000090931).

Almost surely, 2^18000181861 is an apocalyptic number.

It is an amenable number.

18000181861 is a deficient number, since it is larger than the sum of its proper divisors (1).

18000181861 is an equidigital number, since it uses as much as digits as its factorization.

18000181861 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3072, while the sum is 34.

The spelling of 18000181861 in words is "eighteen billion, one hundred eighty-one thousand, eight hundred sixty-one".