161366209 has 3 divisors (see below), whose sum is σ = 161378913. Its totient is φ = 161353506.

The previous prime is 161366203. The next prime is 161366267. The reversal of 161366209 is 902663161.

The square root of 161366209 is 12703.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 902663161 = 17 ⋅53097833.

It is not a de Polignac number, because 161366209 - 2⁷ = 161366081 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (161366203) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 6352 + ... + 19054.

It is an arithmetic number, because the mean of its divisors is an integer number (53792971).

Almost surely, 2^161366209 is an apocalyptic number.

161366209 is the 12703-rd square number.

161366209 is the 6352-nd centered octagonal number.

It is an amenable number.

161366209 is a deficient number, since it is larger than the sum of its proper divisors (12704).

161366209 is an frugal number, since it uses more digits than its factorization.

161366209 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25406 (or 12703 counting only the distinct ones).

The product of its (nonzero) digits is 11664, while the sum is 34.

The cubic root of 161366209 is about 544.4243384387.

Multiplying 161366209 by its product of nonzero digits (11664), we get a square (1882175461776 = 1371924²).

The spelling of 161366209 in words is "one hundred sixty-one million, three hundred sixty-six thousand, two hundred nine".