181899161 has 2 divisors, whose sum is σ = 181899162. Its totient is φ = 181899160.

The previous prime is 181899131. The next prime is 181899181. The reversal of 181899161 is 161998181.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 154231561 + 27667600 = 12419^2 + 5260^2 .

It is an emirp because it is prime and its reverse (161998181) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 181899161 - 2¹⁰ = 181898137 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (181899121) 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, 90949580 + 90949581.

It is an arithmetic number, because the mean of its divisors is an integer number (90949581).

Almost surely, 2^181899161 is an apocalyptic number.

It is an amenable number.

181899161 is a deficient number, since it is larger than the sum of its proper divisors (1).

181899161 is an equidigital number, since it uses as much as digits as its factorization.

181899161 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 31104, while the sum is 44.

The square root of 181899161 is about 13486.9997034181. Note that the first 3 decimals coincide. The cubic root of 181899161 is about 566.6004285130.

The spelling of 181899161 in words is "one hundred eighty-one million, eight hundred ninety-nine thousand, one hundred sixty-one".