665001 has 12 divisors (see below), whose sum is σ = 987012. Its totient is φ = 431136.

The previous prime is 664997. The next prime is 665011. The reversal of 665001 is 100566.

665001 is a `hidden beast` number, since 665 + 0 + 0 + 1 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 275625 + 389376 = 525^2 + 624^2 .

It is not a de Polignac number, because 665001 - 2² = 664997 is a prime.

It is a Curzon number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 665001.

It is not an unprimeable number, because it can be changed into a prime (665011) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 666 + ... + 1331.

It is an arithmetic number, because the mean of its divisors is an integer number (82251).

2⁶⁶⁵⁰⁰¹ is an apocalyptic number.

665001 is the 666-th pentagonal number.

It is an amenable number.

665001 is a deficient number, since it is larger than the sum of its proper divisors (322011).

665001 is a wasteful number, since it uses less digits than its factorization.

665001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2040 (or 2037 counting only the distinct ones).

The product of its (nonzero) digits is 180, while the sum is 18.

The square root of 665001 is about 815.4759346541. The cubic root of 665001 is about 87.2852311038.

Adding to 665001 its reverse (100566), we get a palindrome (765567).

The spelling of 665001 in words is "six hundred sixty-five thousand, one".