99865 has 4 divisors (see below), whose sum is σ = 119844. Its totient is φ = 79888.

The previous prime is 99859. The next prime is 99871. The reversal of 99865 is 56899.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 56899 = 17 ⋅3347.

It is an interprime number because it is at equal distance from previous prime (99859) and next prime (99871).

It can be written as a sum of positive squares in 2 ways, for example, as 36864 + 63001 = 192^2 + 251^2 .

It is a cyclic number.

It is not a de Polignac number, because 99865 - 2⁵ = 99833 is a prime.

It is an Ulam number.

It is a Duffinian number.

99865 is a lucky number.

It is a nialpdrome in base 10.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 9982 + ... + 9991.

It is an arithmetic number, because the mean of its divisors is an integer number (29961).

2⁹⁹⁸⁶⁵ is an apocalyptic number.

It is an amenable number.

99865 is a deficient number, since it is larger than the sum of its proper divisors (19979).

99865 is a wasteful number, since it uses less digits than its factorization.

99865 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19978.

The product of its digits is 19440, while the sum is 37.

The square root of 99865 is about 316.0142401855. The cubic root of 99865 is about 46.3949917801.

The spelling of 99865 in words is "ninety-nine thousand, eight hundred sixty-five".