181661013 has 12 divisors (see below), whose sum is σ = 263528460. Its totient is φ = 120586176.

The previous prime is 181660987. The next prime is 181661027. The reversal of 181661013 is 310166181.

It can be written as a sum of positive squares in 2 ways, for example, as 64112049 + 117548964 = 8007^2 + 10842^2 .

It is not a de Polignac number, because 181661013 - 2⁵ = 181660981 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (181641013) 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 11 ways as a sum of consecutive naturals, for example, 41218 + ... + 45411.

It is an arithmetic number, because the mean of its divisors is an integer number (21960705).

Almost surely, 2^181661013 is an apocalyptic number.

It is an amenable number.

181661013 is a deficient number, since it is larger than the sum of its proper divisors (81867447).

181661013 is a wasteful number, since it uses less digits than its factorization.

181661013 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 86868 (or 86865 counting only the distinct ones).

The product of its (nonzero) digits is 864, while the sum is 27.

The square root of 181661013 is about 13478.1680134950. The cubic root of 181661013 is about 566.3530502625.

The spelling of 181661013 in words is "one hundred eighty-one million, six hundred sixty-one thousand, thirteen".