181998181 has 2 divisors, whose sum is σ = 181998182. Its totient is φ = 181998180.

The previous prime is 181998161. The next prime is 181998199. The reversal of 181998181 is 181899181.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 167935681 + 14062500 = 12959^2 + 3750^2 .

It is an emirp because it is prime and its reverse (181899181) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 181998181 - 2¹⁷ = 181867109 is a prime.

It is a super-2 number, since 2×181998181² = 66246675774617522, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (181998101) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 90999090 + 90999091.

It is an arithmetic number, because the mean of its divisors is an integer number (90999091).

Almost surely, 2^181998181 is an apocalyptic number.

It is an amenable number.

181998181 is a deficient number, since it is larger than the sum of its proper divisors (1).

181998181 is an equidigital number, since it uses as much as digits as its factorization.

181998181 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 41472, while the sum is 46.

The square root of 181998181 is about 13490.6701464382. The cubic root of 181998181 is about 566.7032228243.

It can be divided in two parts, 1819 and 98181, that added together give a 5-th power (100000 = 10⁵).

The spelling of 181998181 in words is "one hundred eighty-one million, nine hundred ninety-eight thousand, one hundred eighty-one".