166561567 has 4 divisors (see below), whose sum is σ = 166593240. Its totient is φ = 166529896.

The previous prime is 166561553. The next prime is 166561573. The reversal of 166561567 is 765165661.

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

It is a cyclic number.

It is not a de Polignac number, because 166561567 - 2¹⁹ = 166037279 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 (166561067) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5848 + ... + 19165.

It is an arithmetic number, because the mean of its divisors is an integer number (41648310).

Almost surely, 2^166561567 is an apocalyptic number.

166561567 is a deficient number, since it is larger than the sum of its proper divisors (31673).

166561567 is an equidigital number, since it uses as much as digits as its factorization.

166561567 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31672.

The product of its digits is 226800, while the sum is 43.

The square root of 166561567 is about 12905.8733528576. The cubic root of 166561567 is about 550.2055066743.

The spelling of 166561567 in words is "one hundred sixty-six million, five hundred sixty-one thousand, five hundred sixty-seven".