181406909 has 2 divisors, whose sum is σ = 181406910. Its totient is φ = 181406908.

The previous prime is 181406899. The next prime is 181406941. The reversal of 181406909 is 909604181.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 170824900 + 10582009 = 13070^2 + 3253^2 .

It is an emirp because it is prime and its reverse (909604181) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 181406909 - 2¹² = 181402813 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (181409909) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 90703454 + 90703455.

It is an arithmetic number, because the mean of its divisors is an integer number (90703455).

Almost surely, 2^181406909 is an apocalyptic number.

It is an amenable number.

181406909 is a deficient number, since it is larger than the sum of its proper divisors (1).

181406909 is an equidigital number, since it uses as much as digits as its factorization.

181406909 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 15552, while the sum is 38.

The square root of 181406909 is about 13468.7382111317. The cubic root of 181406909 is about 566.0888590526.

The spelling of 181406909 in words is "one hundred eighty-one million, four hundred six thousand, nine hundred nine".