16865 has 4 divisors (see below), whose sum is σ = 20244. Its totient is φ = 13488.

The previous prime is 16843. The next prime is 16871. The reversal of 16865 is 56861.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 56861 = 7 ⋅8123.

It can be written as a sum of positive squares in 2 ways, for example, as 12769 + 4096 = 113^2 + 64^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-16865 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1682 + ... + 1691.

It is an arithmetic number, because the mean of its divisors is an integer number (5061).

2¹⁶⁸⁶⁵ is an apocalyptic number.

It is an amenable number.

16865 is a deficient number, since it is larger than the sum of its proper divisors (3379).

16865 is an equidigital number, since it uses as much as digits as its factorization.

16865 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3378.

The product of its digits is 1440, while the sum is 26.

The square root of 16865 is about 129.8653148458. The cubic root of 16865 is about 25.6445716036.

The spelling of 16865 in words is "sixteen thousand, eight hundred sixty-five".