161740809 has 12 divisors (see below), whose sum is σ = 233736516. Its totient is φ = 107776032.

The previous prime is 161740793. The next prime is 161740847. The reversal of 161740809 is 908047161.

It can be written as a sum of positive squares in 2 ways, for example, as 11923209 + 149817600 = 3453^2 + 12240^2 .

It is not a de Polignac number, because 161740809 - 2⁴ = 161740793 is a prime.

It is not an unprimeable number, because it can be changed into a prime (161740309) 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 in 11 ways as a sum of consecutive naturals, for example, 31807 + ... + 36539.

It is an arithmetic number, because the mean of its divisors is an integer number (19478043).

Almost surely, 2^161740809 is an apocalyptic number.

It is an amenable number.

161740809 is a deficient number, since it is larger than the sum of its proper divisors (71995707).

161740809 is a wasteful number, since it uses less digits than its factorization.

161740809 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8536 (or 8533 counting only the distinct ones).

The product of its (nonzero) digits is 12096, while the sum is 36.

The square root of 161740809 is about 12717.7360013487. The cubic root of 161740809 is about 544.8452934617.

The spelling of 161740809 in words is "one hundred sixty-one million, seven hundred forty thousand, eight hundred nine".