99805 has 4 divisors (see below), whose sum is σ = 119772. Its totient is φ = 79840.

The previous prime is 99793. The next prime is 99809. The reversal of 99805 is 50899.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 50899 = 23 ⋅2213.

It can be written as a sum of positive squares in 2 ways, for example, as 68121 + 31684 = 261^2 + 178^2 .

It is a de Polignac number, because none of the positive numbers 2^k-99805 is a prime.

It is a super-2 number, since 2×99805² = 19922076050, which contains 22 as substring.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (99809) 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, 9976 + ... + 9985.

It is an arithmetic number, because the mean of its divisors is an integer number (29943).

2⁹⁹⁸⁰⁵ is an apocalyptic number.

It is an amenable number.

99805 is a deficient number, since it is larger than the sum of its proper divisors (19967).

99805 is a wasteful number, since it uses less digits than its factorization.

99805 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19966.

The product of its (nonzero) digits is 3240, while the sum is 31.

The square root of 99805 is about 315.9192934912. The cubic root of 99805 is about 46.3856983767.

The spelling of 99805 in words is "ninety-nine thousand, eight hundred five".