181911161 has 2 divisors, whose sum is σ = 181911162. Its totient is φ = 181911160.

The previous prime is 181911151. The next prime is 181911253. The reversal of 181911161 is 161119181.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 99900025 + 82011136 = 9995^2 + 9056^2 .It is also a bemirp because it and its reverse can be mirrored producing other two distinct primes, 191116181 and 181611191.

It is a cyclic number.

It is not a de Polignac number, because 181911161 - 2²⁶ = 114802297 is a prime.

It is not a weakly prime, because it can be changed into another prime (181911151) 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, 90955580 + 90955581.

It is an arithmetic number, because the mean of its divisors is an integer number (90955581).

Almost surely, 2^181911161 is an apocalyptic number.

It is an amenable number.

181911161 is a deficient number, since it is larger than the sum of its proper divisors (1).

181911161 is an equidigital number, since it uses as much as digits as its factorization.

181911161 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 432, while the sum is 29.

The square root of 181911161 is about 13487.4445689315. Note that the first 3 decimals coincide. The cubic root of 181911161 is about 566.6128878990.

The spelling of 181911161 in words is "one hundred eighty-one million, nine hundred eleven thousand, one hundred sixty-one".