165986 has 8 divisors (see below), whose sum is σ = 251100. Its totient is φ = 82288.

The previous prime is 165983. The next prime is 166013. The reversal of 165986 is 689561.

It can be written as a sum of positive squares in 2 ways, for example, as 133225 + 32761 = 365^2 + 181^2 .

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

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (165983) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 20 + ... + 576.

2¹⁶⁵⁹⁸⁶ is an apocalyptic number.

165986 is a deficient number, since it is larger than the sum of its proper divisors (85114).

165986 is a wasteful number, since it uses less digits than its factorization.

165986 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 708.

The product of its digits is 12960, while the sum is 35.

The square root of 165986 is about 407.4137945627. The cubic root of 165986 is about 54.9571015353.

The spelling of 165986 in words is "one hundred sixty-five thousand, nine hundred eighty-six".