181309909 has 6 divisors (see below), whose sum is σ = 199291190. Its totient is φ = 164827080.

The previous prime is 181309907. The next prime is 181309937. The reversal of 181309909 is 909903181.

It can be written as a sum of positive squares in only one way, i.e., 166487409 + 14822500 = 12903^2 + 3850^2 .

It is not a de Polignac number, because 181309909 - 2¹ = 181309907 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (181309903) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 749094 + ... + 749335.

Almost surely, 2^181309909 is an apocalyptic number.

It is an amenable number.

181309909 is a deficient number, since it is larger than the sum of its proper divisors (17981281).

181309909 is a wasteful number, since it uses less digits than its factorization.

181309909 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1498451 (or 1498440 counting only the distinct ones).

The product of its (nonzero) digits is 17496, while the sum is 40.

The square root of 181309909 is about 13465.1367984139. The cubic root of 181309909 is about 565.9879433642.

The spelling of 181309909 in words is "one hundred eighty-one million, three hundred nine thousand, nine hundred nine".