181605556189 has 2 divisors, whose sum is σ = 181605556190. Its totient is φ = 181605556188.

The previous prime is 181605556159. The next prime is 181605556229. The reversal of 181605556189 is 981655506181.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 180922622500 + 682933689 = 425350^2 + 26133^2 .

It is a cyclic number.

It is not a de Polignac number, because 181605556189 - 2⁷ = 181605556061 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (181605556159) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 90802778094 + 90802778095.

It is an arithmetic number, because the mean of its divisors is an integer number (90802778095).

Almost surely, 2^181605556189 is an apocalyptic number.

It is an amenable number.

181605556189 is a deficient number, since it is larger than the sum of its proper divisors (1).

181605556189 is an equidigital number, since it uses as much as digits as its factorization.

181605556189 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2592000, while the sum is 55.

The spelling of 181605556189 in words is "one hundred eighty-one billion, six hundred five million, five hundred fifty-six thousand, one hundred eighty-nine".