164973256561 has 3 divisors (see below), whose sum is σ = 164973662731. Its totient is φ = 164972850392.

The previous prime is 164973256529. The next prime is 164973256589. The reversal of 164973256561 is 165652379461.

It is a happy number.

The square root of 164973256561 is 406169.

It is a perfect power (a square), and thus also a powerful number.

164973256561 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in only one way, i.e., 164324026161 + 649230400 = 405369^2 + 25480^2 .

It is not a de Polignac number, because 164973256561 - 2⁵ = 164973256529 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (164973254561) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 203085 + ... + 609253.

Almost surely, 2^164973256561 is an apocalyptic number.

164973256561 is the 406169-th square number.

164973256561 is the 203085-th centered octagonal number.

It is an amenable number.

164973256561 is a deficient number, since it is larger than the sum of its proper divisors (406170).

164973256561 is an frugal number, since it uses more digits than its factorization.

164973256561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 812338 (or 406169 counting only the distinct ones).

The product of its digits is 8164800, while the sum is 55.

The spelling of 164973256561 in words is "one hundred sixty-four billion, nine hundred seventy-three million, two hundred fifty-six thousand, five hundred sixty-one".