165665 has 8 divisors (see below), whose sum is σ = 210600. Its totient is φ = 124672.

The previous prime is 165653. The next prime is 165667. The reversal of 165665 is 566561.

It can be written as a sum of positive squares in 4 ways, for example, as 58081 + 107584 = 241^2 + 328^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 165665 - 2⁶ = 165601 is a prime.

It is not an unprimeable number, because it can be changed into a prime (165667) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 890 + ... + 1059.

It is an arithmetic number, because the mean of its divisors is an integer number (26325).

2¹⁶⁵⁶⁶⁵ is an apocalyptic number.

It is an amenable number.

165665 is a deficient number, since it is larger than the sum of its proper divisors (44935).

165665 is a wasteful number, since it uses less digits than its factorization.

165665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1971.

The product of its digits is 5400, while the sum is 29.

The square root of 165665 is about 407.0196555450. The cubic root of 165665 is about 54.9216515296.

The spelling of 165665 in words is "one hundred sixty-five thousand, six hundred sixty-five".