163665 has 12 divisors (see below), whose sum is σ = 283764. Its totient is φ = 87264.

The previous prime is 163661. The next prime is 163673. The reversal of 163665 is 566361.

It can be written as a sum of positive squares in 2 ways, for example, as 25281 + 138384 = 159^2 + 372^2 .

It is not a de Polignac number, because 163665 - 2² = 163661 is a prime.

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (163661) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1774 + ... + 1863.

It is an arithmetic number, because the mean of its divisors is an integer number (23647).

2¹⁶³⁶⁶⁵ is an apocalyptic number.

163665 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

163665 is a deficient number, since it is larger than the sum of its proper divisors (120099).

163665 is a wasteful number, since it uses less digits than its factorization.

163665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3648 (or 3645 counting only the distinct ones).

The product of its digits is 3240, while the sum is 27.

The square root of 163665 is about 404.5553114223. Note that the first 3 decimals coincide. The cubic root of 163665 is about 54.6997412053.

It can be divided in two parts, 163 and 665, that added together give a palindrome (828).

The spelling of 163665 in words is "one hundred sixty-three thousand, six hundred sixty-five".