181868681 has 4 divisors (see below), whose sum is σ = 181901892. Its totient is φ = 181835472.

The previous prime is 181868677. The next prime is 181868711. The reversal of 181868681 is 186868181.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 186868181 = 127 ⋅1471403.

It can be written as a sum of positive squares in 2 ways, for example, as 159163456 + 22705225 = 12616^2 + 4765^2 .

It is a cyclic number.

It is not a de Polignac number, because 181868681 - 2² = 181868677 is a prime.

It is a super-2 number, since 2×181868681² = 66152434257359522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (181868611) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6230 + ... + 20063.

It is an arithmetic number, because the mean of its divisors is an integer number (45475473).

Almost surely, 2^181868681 is an apocalyptic number.

It is an amenable number.

181868681 is a deficient number, since it is larger than the sum of its proper divisors (33211).

181868681 is an equidigital number, since it uses as much as digits as its factorization.

181868681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33210.

The product of its digits is 147456, while the sum is 47.

The square root of 181868681 is about 13485.8696790381. The cubic root of 181868681 is about 566.5687792085.

The spelling of 181868681 in words is "one hundred eighty-one million, eight hundred sixty-eight thousand, six hundred eighty-one".