100865 has 4 divisors (see below), whose sum is σ = 121044. Its totient is φ = 80688.

The previous prime is 100853. The next prime is 100907. The reversal of 100865 is 568001.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 78961 + 21904 = 281^2 + 148^2 .

It is a cyclic number.

It is not a de Polignac number, because 100865 - 2⁶ = 100801 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 10082 + ... + 10091.

It is an arithmetic number, because the mean of its divisors is an integer number (30261).

It is a Proth number, since it is equal to 197 ⋅ 2⁹ + 1 and 197 < 2⁹.

2¹⁰⁰⁸⁶⁵ is an apocalyptic number.

It is an amenable number.

100865 is a deficient number, since it is larger than the sum of its proper divisors (20179).

100865 is an equidigital number, since it uses as much as digits as its factorization.

100865 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20178.

The product of its (nonzero) digits is 240, while the sum is 20.

The square root of 100865 is about 317.5925062088. The cubic root of 100865 is about 46.5493367743.

Adding to 100865 its reverse (568001), we get a palindrome (668866).

The spelling of 100865 in words is "one hundred thousand, eight hundred sixty-five".