161309809 has 4 divisors (see below), whose sum is σ = 162275904. Its totient is φ = 160343716.

The previous prime is 161309801. The next prime is 161309851. The reversal of 161309809 is 908903161.

161309809 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 908903161 = 331 ⋅2745931.

It is a cyclic number.

It is not a de Polignac number, because 161309809 - 2³ = 161309801 is a prime.

It is not an unprimeable number, because it can be changed into a prime (161309801) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 482797 + ... + 483130.

It is an arithmetic number, because the mean of its divisors is an integer number (40568976).

Almost surely, 2^161309809 is an apocalyptic number.

It is an amenable number.

161309809 is a deficient number, since it is larger than the sum of its proper divisors (966095).

161309809 is an equidigital number, since it uses as much as digits as its factorization.

161309809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 966094.

The product of its (nonzero) digits is 11664, while the sum is 37.

The square root of 161309809 is about 12700.7798579457. The cubic root of 161309809 is about 544.3609027894.

The spelling of 161309809 in words is "one hundred sixty-one million, three hundred nine thousand, eight hundred nine".