181938161 has 4 divisors (see below), whose sum is σ = 183982500. Its totient is φ = 179893824.

The previous prime is 181938157. The next prime is 181938179. The reversal of 181938161 is 161839181.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 25563136 + 156375025 = 5056^2 + 12505^2 .

It is a cyclic number.

It is not a de Polignac number, because 181938161 - 2² = 181938157 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (181938121) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1022036 + ... + 1022213.

It is an arithmetic number, because the mean of its divisors is an integer number (45995625).

Almost surely, 2^181938161 is an apocalyptic number.

It is an amenable number.

181938161 is a deficient number, since it is larger than the sum of its proper divisors (2044339).

181938161 is an equidigital number, since it uses as much as digits as its factorization.

181938161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2044338.

The product of its digits is 10368, while the sum is 38.

The square root of 181938161 is about 13488.4454626914. The cubic root of 181938161 is about 566.6409195145.

The spelling of 181938161 in words is "one hundred eighty-one million, nine hundred thirty-eight thousand, one hundred sixty-one".