164561 has 6 divisors (see below), whose sum is σ = 170370. Its totient is φ = 158928.

The previous prime is 164531. The next prime is 164569. The reversal of 164561 is 165461.

It can be written as a sum of positive squares in only one way, i.e., 118336 + 46225 = 344^2 + 215^2 .

It is a de Polignac number, because none of the positive numbers 2^k-164561 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (164569) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1805 + ... + 1893.

It is an arithmetic number, because the mean of its divisors is an integer number (28395).

2¹⁶⁴⁵⁶¹ is an apocalyptic number.

It is an amenable number.

164561 is a deficient number, since it is larger than the sum of its proper divisors (5809).

164561 is an frugal number, since it uses more digits than its factorization.

164561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 175 (or 132 counting only the distinct ones).

The product of its digits is 720, while the sum is 23.

The square root of 164561 is about 405.6611886784. The cubic root of 164561 is about 54.7993792886.

Subtracting 164561 from its reverse (165461), we obtain a square (900 = 30²).

The spelling of 164561 in words is "one hundred sixty-four thousand, five hundred sixty-one".