165921 has 8 divisors (see below), whose sum is σ = 252864. Its totient is φ = 94800.

The previous prime is 165901. The next prime is 165931. The reversal of 165921 is 129561.

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

It is not a de Polignac number, because 165921 - 2⁶ = 165857 is a prime.

It is a Curzon number.

165921 is a lucky number.

It is a plaindrome in base 14.

It is a junction number, because it is equal to n+sod(n) for n = 165891 and 165900.

It is not an unprimeable number, because it can be changed into a prime (165901) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3930 + ... + 3971.

It is an arithmetic number, because the mean of its divisors is an integer number (31608).

2¹⁶⁵⁹²¹ is an apocalyptic number.

It is an amenable number.

165921 is a deficient number, since it is larger than the sum of its proper divisors (86943).

165921 is an equidigital number, since it uses as much as digits as its factorization.

165921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7911.

The product of its digits is 540, while the sum is 24.

The square root of 165921 is about 407.3340152749. The cubic root of 165921 is about 54.9499268780.

The spelling of 165921 in words is "one hundred sixty-five thousand, nine hundred twenty-one".