9905 has 8 divisors (see below), whose sum is σ = 13632. Its totient is φ = 6768.

The previous prime is 9901. The next prime is 9907. The reversal of 9905 is 5099.

9905 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It is a cyclic number.

It is not a de Polignac number, because 9905 - 2² = 9901 is a prime.

It is a Duffinian number.

It is a plaindrome in base 13.

It is not an unprimeable number, because it can be changed into a prime (9901) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 107 + ... + 176.

It is an arithmetic number, because the mean of its divisors is an integer number (1704).

2⁹⁹⁰⁵ is an apocalyptic number.

It is an amenable number.

9905 is a deficient number, since it is larger than the sum of its proper divisors (3727).

9905 is a wasteful number, since it uses less digits than its factorization.

9905 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 295.

The product of its (nonzero) digits is 405, while the sum is 23.

The square root of 9905 is about 99.5238664844. The cubic root of 9905 is about 21.4759059457.

It can be divided in two parts, 990 and 5, that multiplied together give a triangular number (4950 = T₉₉).

The spelling of 9905 in words is "nine thousand, nine hundred five".