181660889 has 2 divisors, whose sum is σ = 181660890. Its totient is φ = 181660888.

The previous prime is 181660859. The next prime is 181660909. The reversal of 181660889 is 988066181.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 181575625 + 85264 = 13475^2 + 292^2 .

It is an emirp because it is prime and its reverse (988066181) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 181660889 - 2¹² = 181656793 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (181660819) 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, 90830444 + 90830445.

It is an arithmetic number, because the mean of its divisors is an integer number (90830445).

Almost surely, 2^181660889 is an apocalyptic number.

It is an amenable number.

181660889 is a deficient number, since it is larger than the sum of its proper divisors (1).

181660889 is an equidigital number, since it uses as much as digits as its factorization.

181660889 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 165888, while the sum is 47.

The square root of 181660889 is about 13478.1634134625. The cubic root of 181660889 is about 566.3529214001.

The spelling of 181660889 in words is "one hundred eighty-one million, six hundred sixty thousand, eight hundred eighty-nine".