181000989 has 72 divisors (see below), whose sum is σ = 307753992. Its totient is φ = 101836800.

The previous prime is 181000949. The next prime is 181000993. The reversal of 181000989 is 989000181.

It can be written as a sum of positive squares in 12 ways, for example, as 2377764 + 178623225 = 1542^2 + 13365^2 .

It is not a de Polignac number, because 181000989 - 2⁸ = 181000733 is a prime.

It is a super-2 number, since 2×181000989² = 65522716037956242, which contains 22 as substring.

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (181000949) by changing a digit.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 1792039 + ... + 1792139.

It is an arithmetic number, because the mean of its divisors is an integer number (4274361).

Almost surely, 2^181000989 is an apocalyptic number.

It is an amenable number.

181000989 is a deficient number, since it is larger than the sum of its proper divisors (126753003).

181000989 is a wasteful number, since it uses less digits than its factorization.

181000989 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 207 (or 187 counting only the distinct ones).

The product of its (nonzero) digits is 5184, while the sum is 36.

The square root of 181000989 is about 13453.6608029190. The cubic root of 181000989 is about 565.6663128621. Note that the first 3 decimals are identical.

The spelling of 181000989 in words is "one hundred eighty-one million, nine hundred eighty-nine", and thus it is an aban number.