201665 has 8 divisors (see below), whose sum is σ = 246888. Its totient is φ = 158080.

The previous prime is 201661. The next prime is 201667. The reversal of 201665 is 566102.

It can be written as a sum of positive squares in 4 ways, for example, as 961 + 200704 = 31^2 + 448^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 201665 - 2² = 201661 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a nialpdrome in base 12.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (201661) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 116 + ... + 645.

It is an arithmetic number, because the mean of its divisors is an integer number (30861).

2²⁰¹⁶⁶⁵ is an apocalyptic number.

It is an amenable number.

201665 is a deficient number, since it is larger than the sum of its proper divisors (45223).

201665 is an equidigital number, since it uses as much as digits as its factorization.

201665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 819.

The product of its (nonzero) digits is 360, while the sum is 20.

The square root of 201665 is about 449.0712638324. The cubic root of 201665 is about 58.6421894848.

Adding to 201665 its reverse (566102), we get a palindrome (767767).

The spelling of 201665 in words is "two hundred one thousand, six hundred sixty-five".