165001321 has 4 divisors (see below), whose sum is σ = 166300672. Its totient is φ = 163701972.

The previous prime is 165001289. The next prime is 165001351. The reversal of 165001321 is 123100561.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 123100561 = 8867 ⋅13883.

It is a cyclic number.

It is not a de Polignac number, because 165001321 - 2⁵ = 165001289 is a prime.

It is a Duffinian number.

It is a nialpdrome in base 15.

It is not an unprimeable number, because it can be changed into a prime (165001351) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 649485 + ... + 649738.

It is an arithmetic number, because the mean of its divisors is an integer number (41575168).

Almost surely, 2^165001321 is an apocalyptic number.

It is an amenable number.

165001321 is a deficient number, since it is larger than the sum of its proper divisors (1299351).

165001321 is a wasteful number, since it uses less digits than its factorization.

165001321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1299350.

The product of its (nonzero) digits is 180, while the sum is 19.

The square root of 165001321 is about 12845.2839984175. The cubic root of 165001321 is about 548.4821189625.

Adding to 165001321 its reverse (123100561), we get a palindrome (288101882).

The spelling of 165001321 in words is "one hundred sixty-five million, one thousand, three hundred twenty-one".