161211161 has 4 divisors (see below), whose sum is σ = 161238324. Its totient is φ = 161184000.

The previous prime is 161211157. The next prime is 161211199. The reversal of 161211161 is 161112161.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 38688400 + 122522761 = 6220^2 + 11069^2 .

It is a cyclic number.

It is not a de Polignac number, because 161211161 - 2² = 161211157 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (161211101) 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, 440 + ... + 17961.

It is an arithmetic number, because the mean of its divisors is an integer number (40309581).

Almost surely, 2^161211161 is an apocalyptic number.

It is an amenable number.

161211161 is a deficient number, since it is larger than the sum of its proper divisors (27163).

161211161 is an equidigital number, since it uses as much as digits as its factorization.

161211161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27162.

The product of its digits is 72, while the sum is 20.

The square root of 161211161 is about 12696.8957229710. The cubic root of 161211161 is about 544.2499133316.

The spelling of 161211161 in words is "one hundred sixty-one million, two hundred eleven thousand, one hundred sixty-one".