161205161 has 4 divisors (see below), whose sum is σ = 173605572. Its totient is φ = 148804752.

The previous prime is 161205103. The next prime is 161205167. The reversal of 161205161 is 161502161.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 161502161 = 6961 ⋅23201.

It can be written as a sum of positive squares in 2 ways, for example, as 28955161 + 132250000 = 5381^2 + 11500^2 .

It is a cyclic number.

It is not a de Polignac number, because 161205161 - 2¹⁰ = 161204137 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (161205167) 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, 6200186 + ... + 6200211.

It is an arithmetic number, because the mean of its divisors is an integer number (43401393).

Almost surely, 2^161205161 is an apocalyptic number.

It is an amenable number.

161205161 is a deficient number, since it is larger than the sum of its proper divisors (12400411).

161205161 is a wasteful number, since it uses less digits than its factorization.

161205161 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12400410.

The product of its (nonzero) digits is 360, while the sum is 23.

The square root of 161205161 is about 12696.6594425463. The cubic root of 161205161 is about 544.2431612350.

The spelling of 161205161 in words is "one hundred sixty-one million, two hundred five thousand, one hundred sixty-one".