181242209 has 2 divisors, whose sum is σ = 181242210. Its totient is φ = 181242208.

The previous prime is 181242161. The next prime is 181242211. The reversal of 181242209 is 902242181.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 179560000 + 1682209 = 13400^2 + 1297^2 .

It is an emirp because it is prime and its reverse (902242181) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 181242209 - 2⁸ = 181241953 is a prime.

Together with 181242211, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (181242409) 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, 90621104 + 90621105.

It is an arithmetic number, because the mean of its divisors is an integer number (90621105).

Almost surely, 2^181242209 is an apocalyptic number.

It is an amenable number.

181242209 is a deficient number, since it is larger than the sum of its proper divisors (1).

181242209 is an equidigital number, since it uses as much as digits as its factorization.

181242209 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2304, while the sum is 29.

The square root of 181242209 is about 13462.6226642508. The cubic root of 181242209 is about 565.9174891272.

The spelling of 181242209 in words is "one hundred eighty-one million, two hundred forty-two thousand, two hundred nine".