181561923097 has 2 divisors, whose sum is σ = 181561923098. Its totient is φ = 181561923096.

The previous prime is 181561923079. The next prime is 181561923113. The reversal of 181561923097 is 790329165181.

181561923097 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

Together with previous prime (181561923079) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 137385870336 + 44176052761 = 370656^2 + 210181^2 .

It is a cyclic number.

It is not a de Polignac number, because 181561923097 - 2²³ = 181553534489 is a prime.

It is not a weakly prime, because it can be changed into another prime (181561923997) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 90780961548 + 90780961549.

It is an arithmetic number, because the mean of its divisors is an integer number (90780961549).

Almost surely, 2^181561923097 is an apocalyptic number.

It is an amenable number.

181561923097 is a deficient number, since it is larger than the sum of its proper divisors (1).

181561923097 is an equidigital number, since it uses as much as digits as its factorization.

181561923097 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 816480, while the sum is 52.

The spelling of 181561923097 in words is "one hundred eighty-one billion, five hundred sixty-one million, nine hundred twenty-three thousand, ninety-seven".