165507021 has 12 divisors (see below), whose sum is σ = 239215548. Its totient is φ = 110268864.

The previous prime is 165506993. The next prime is 165507029. The reversal of 165507021 is 120705561.

165507021 is a `hidden beast` number, since 1 + 655 + 0 + 7 + 0 + 2 + 1 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 158004900 + 7502121 = 12570^2 + 2739^2 .

It is not a de Polignac number, because 165507021 - 2¹⁰ = 165505997 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (165507029) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 12411 + ... + 22023.

It is an arithmetic number, because the mean of its divisors is an integer number (19934629).

Almost surely, 2^165507021 is an apocalyptic number.

It is an amenable number.

165507021 is a deficient number, since it is larger than the sum of its proper divisors (73708527).

165507021 is a wasteful number, since it uses less digits than its factorization.

165507021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11532 (or 11529 counting only the distinct ones).

The product of its (nonzero) digits is 2100, while the sum is 27.

The square root of 165507021 is about 12864.9532062888. The cubic root of 165507021 is about 549.0418812048.

The spelling of 165507021 in words is "one hundred sixty-five million, five hundred seven thousand, twenty-one".