181885681 has 2 divisors, whose sum is σ = 181885682. Its totient is φ = 181885680.

The previous prime is 181885661. The next prime is 181885687. The reversal of 181885681 is 186588181.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 114383025 + 67502656 = 10695^2 + 8216^2 .

It is a cyclic number.

It is not a de Polignac number, because 181885681 - 2¹³ = 181877489 is a prime.

It is a super-2 number, since 2×181885681² = 66164801905667522, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (181885687) 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, 90942840 + 90942841.

It is an arithmetic number, because the mean of its divisors is an integer number (90942841).

Almost surely, 2^181885681 is an apocalyptic number.

It is an amenable number.

181885681 is a deficient number, since it is larger than the sum of its proper divisors (1).

181885681 is an equidigital number, since it uses as much as digits as its factorization.

181885681 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 122880, while the sum is 46.

The square root of 181885681 is about 13486.4999536574. The cubic root of 181885681 is about 566.5864318157.

The spelling of 181885681 in words is "one hundred eighty-one million, eight hundred eighty-five thousand, six hundred eighty-one".