165204021 has 16 divisors (see below), whose sum is σ = 225089280. Its totient is φ = 107739840.

The previous prime is 165203999. The next prime is 165204077. The reversal of 165204021 is 120402561.

It is not a de Polignac number, because 165204021 - 2⁵ = 165203989 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (165204121) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 60516 + ... + 63186.

It is an arithmetic number, because the mean of its divisors is an integer number (14068080).

Almost surely, 2^165204021 is an apocalyptic number.

It is an amenable number.

165204021 is a deficient number, since it is larger than the sum of its proper divisors (59885259).

165204021 is a wasteful number, since it uses less digits than its factorization.

165204021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3116.

The product of its (nonzero) digits is 480, while the sum is 21.

The square root of 165204021 is about 12853.1716319358. The cubic root of 165204021 is about 548.7066259133.

Adding to 165204021 its reverse (120402561), we get a palindrome (285606582).

The spelling of 165204021 in words is "one hundred sixty-five million, two hundred four thousand, twenty-one".