9985 has 4 divisors (see below), whose sum is σ = 11988. Its totient is φ = 7984.

The previous prime is 9973. The next prime is 10007. The reversal of 9985 is 5899.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 5899 = 17 ⋅347.

It can be written as a sum of positive squares in 2 ways, for example, as 1521 + 8464 = 39^2 + 92^2 .

It is a cyclic number.

It is not a de Polignac number, because 9985 - 2⁷ = 9857 is a prime.

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 an Ulam number.

It is a Duffinian number.

9985 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 (5) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 994 + ... + 1003.

It is an arithmetic number, because the mean of its divisors is an integer number (2997).

It is a Proth number, since it is equal to 39 ⋅ 2⁸ + 1 and 39 < 2⁸.

2⁹⁹⁸⁵ is an apocalyptic number.

It is an amenable number.

9985 is a deficient number, since it is larger than the sum of its proper divisors (2003).

9985 is a wasteful number, since it uses less digits than its factorization.

9985 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2002.

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

The square root of 9985 is about 99.9249718539. The cubic root of 9985 is about 21.5335693363.

Adding to 9985 its product of digits (3240), we get a square (13225 = 115²).

The spelling of 9985 in words is "nine thousand, nine hundred eighty-five".