166565623 has 4 divisors (see below), whose sum is σ = 190360720. Its totient is φ = 142770528.

The previous prime is 166565599. The next prime is 166565627. The reversal of 166565623 is 326565661.

It is a happy number.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-166565623 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (166565627) 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 3 ways as a sum of consecutive naturals, for example, 11897538 + ... + 11897551.

It is an arithmetic number, because the mean of its divisors is an integer number (47590180).

Almost surely, 2^166565623 is an apocalyptic number.

166565623 is a deficient number, since it is larger than the sum of its proper divisors (23795097).

166565623 is an equidigital number, since it uses as much as digits as its factorization.

166565623 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23795096.

The product of its digits is 194400, while the sum is 40.

The square root of 166565623 is about 12906.0304896587. The cubic root of 166565623 is about 550.2099727214.

The spelling of 166565623 in words is "one hundred sixty-six million, five hundred sixty-five thousand, six hundred twenty-three".