165684561 has 8 divisors (see below), whose sum is σ = 252471744. Its totient is φ = 94676880.

The previous prime is 165684551. The next prime is 165684577. The reversal of 165684561 is 165486561.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 165684561 - 2⁵ = 165684529 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (165684521) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3944850 + ... + 3944891.

It is an arithmetic number, because the mean of its divisors is an integer number (31558968).

Almost surely, 2^165684561 is an apocalyptic number.

It is an amenable number.

165684561 is a deficient number, since it is larger than the sum of its proper divisors (86787183).

165684561 is an equidigital number, since it uses as much as digits as its factorization.

165684561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7889751.

The product of its digits is 172800, while the sum is 42.

The square root of 165684561 is about 12871.8514985219. The cubic root of 165684561 is about 549.2381308083.

The spelling of 165684561 in words is "one hundred sixty-five million, six hundred eighty-four thousand, five hundred sixty-one".