165878161 has 4 divisors (see below), whose sum is σ = 166121712. Its totient is φ = 165634612.

The previous prime is 165878159. The next prime is 165878177. The reversal of 165878161 is 161878561.

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.

It is a cyclic number.

It is not a de Polignac number, because 165878161 - 2¹ = 165878159 is a prime.

It is an alternating number because its digits alternate between odd and even.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (165878561) 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 3 ways as a sum of consecutive naturals, for example, 120751 + ... + 122116.

It is an arithmetic number, because the mean of its divisors is an integer number (41530428).

Almost surely, 2^165878161 is an apocalyptic number.

It is an amenable number.

165878161 is a deficient number, since it is larger than the sum of its proper divisors (243551).

165878161 is an equidigital number, since it uses as much as digits as its factorization.

165878161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 243550.

The product of its digits is 80640, while the sum is 43.

The square root of 165878161 is about 12879.3695886095. The cubic root of 165878161 is about 549.4519731288.

The spelling of 165878161 in words is "one hundred sixty-five million, eight hundred seventy-eight thousand, one hundred sixty-one".