181000091 has 4 divisors (see below), whose sum is σ = 181141800. Its totient is φ = 180858384.

The previous prime is 181000073. The next prime is 181000097. The reversal of 181000091 is 190000181.

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

It is a cyclic number.

It is not a de Polignac number, because 181000091 - 2²⁶ = 113891227 is a prime.

It is a super-2 number, since 2×181000091² = 65522065884016562, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (181000097) 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 in 3 ways as a sum of consecutive naturals, for example, 68921 + ... + 71498.

It is an arithmetic number, because the mean of its divisors is an integer number (45285450).

Almost surely, 2^181000091 is an apocalyptic number.

181000091 is a deficient number, since it is larger than the sum of its proper divisors (141709).

181000091 is a wasteful number, since it uses less digits than its factorization.

181000091 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 141708.

The product of its (nonzero) digits is 72, while the sum is 20.

The square root of 181000091 is about 13453.6274290617. The cubic root of 181000091 is about 565.6653773807.

The spelling of 181000091 in words is "one hundred eighty-one million, ninety-one", and thus it is an aban number.