664322161 has 4 divisors (see below), whose sum is σ = 682276852. Its totient is φ = 646367472.

The previous prime is 664322149. The next prime is 664322171. The reversal of 664322161 is 161223466.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 161223466 = 2 ⋅80611733.

It can be written as a sum of positive squares in 2 ways, for example, as 609102400 + 55219761 = 24680^2 + 7431^2 .

It is a cyclic number.

It is not a de Polignac number, because 664322161 - 2¹¹ = 664320113 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (664322171) 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, 8977290 + ... + 8977363.

It is an arithmetic number, because the mean of its divisors is an integer number (170569213).

Almost surely, 2^664322161 is an apocalyptic number.

It is an amenable number.

664322161 is a deficient number, since it is larger than the sum of its proper divisors (17954691).

664322161 is a wasteful number, since it uses less digits than its factorization.

664322161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17954690.

The product of its digits is 10368, while the sum is 31.

The square root of 664322161 is about 25774.4478311369. The cubic root of 664322161 is about 872.5552047565. Note that the first 3 decimals are identical.

The spelling of 664322161 in words is "six hundred sixty-four million, three hundred twenty-two thousand, one hundred sixty-one".