181891165097 has 2 divisors, whose sum is σ = 181891165098. Its totient is φ = 181891165096.

The previous prime is 181891165073. The next prime is 181891165139. The reversal of 181891165097 is 790561198181.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 136636686736 + 45254478361 = 369644^2 + 212731^2 .

It is a cyclic number.

It is not a de Polignac number, because 181891165097 - 2⁶ = 181891165033 is a prime.

It is a super-2 number, since 2×181891165097² (a number of 23 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (181891165007) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 90945582548 + 90945582549.

It is an arithmetic number, because the mean of its divisors is an integer number (90945582549).

Almost surely, 2^181891165097 is an apocalyptic number.

It is an amenable number.

181891165097 is a deficient number, since it is larger than the sum of its proper divisors (1).

181891165097 is an equidigital number, since it uses as much as digits as its factorization.

181891165097 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1088640, while the sum is 56.

The spelling of 181891165097 in words is "one hundred eighty-one billion, eight hundred ninety-one million, one hundred sixty-five thousand, ninety-seven".