165021021 has 48 divisors (see below), whose sum is σ = 273836160. Its totient is φ = 94966080.

The previous prime is 165021011. The next prime is 165021079. The reversal of 165021021 is 120120561.

165021021 is a `hidden beast` number, since 1 + 650 + 2 + 10 + 2 + 1 = 666.

165021021 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 165021021 - 2⁶ = 165020957 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 165020985 and 165021003.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (165021001) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1204465 + ... + 1204601.

It is an arithmetic number, because the mean of its divisors is an integer number (5704920).

Almost surely, 2^165021021 is an apocalyptic number.

165021021 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

165021021 is a deficient number, since it is larger than the sum of its proper divisors (108815139).

165021021 is a wasteful number, since it uses less digits than its factorization.

165021021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 223 (or 174 counting only the distinct ones).

The product of its (nonzero) digits is 120, while the sum is 18.

The square root of 165021021 is about 12846.0507939211. The cubic root of 165021021 is about 548.5039463994.

Adding to 165021021 its reverse (120120561), we get a palindrome (285141582).

The spelling of 165021021 in words is "one hundred sixty-five million, twenty-one thousand, twenty-one".