165684321 has 24 divisors (see below), whose sum is σ = 267452640. Its totient is φ = 97963200.

The previous prime is 165684293. The next prime is 165684361. The reversal of 165684321 is 123486561.

It is a happy number.

165684321 is a `hidden beast` number, since 165 + 68 + 432 + 1 = 666.

It is not a de Polignac number, because 165684321 - 2²⁵ = 132129889 is a prime.

It is not an unprimeable number, because it can be changed into a prime (165684361) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 16351 + ... + 24468.

It is an arithmetic number, because the mean of its divisors is an integer number (11143860).

Almost surely, 2^165684321 is an apocalyptic number.

165684321 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

165684321 is a deficient number, since it is larger than the sum of its proper divisors (101768319).

165684321 is a wasteful number, since it uses less digits than its factorization.

165684321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40877 (or 40874 counting only the distinct ones).

The product of its digits is 34560, while the sum is 36.

The square root of 165684321 is about 12871.8421758504. The cubic root of 165684321 is about 549.2378656112.

It can be divided in two parts, 165 and 684321, that added together give a palindrome (684486).

The spelling of 165684321 in words is "one hundred sixty-five million, six hundred eighty-four thousand, three hundred twenty-one".