9864 has 24 divisors (see below), whose sum is σ = 26910. Its totient is φ = 3264.

The previous prime is 9859. The next prime is 9871. The reversal of 9864 is 4689.

9864 is an esthetic number in base 8, because in such base its adjacent digits differ by 1.

It can be written as a sum of positive squares in only one way, i.e., 8100 + 1764 = 90^2 + 42^2 .

It is a tau number, because it is divible by the number of its divisors (24).

It is a nude number because it is divisible by every one of its digits.

It is one of the 548 Lynch-Bell numbers.

It is a plaindrome in base 16.

It is a nialpdrome in base 10.

It is an unprimeable number.

9864 is an untouchable number, because it is not equal to the sum of proper divisors of any 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 5 ways as a sum of consecutive naturals, for example, 4 + ... + 140.

2⁹⁸⁶⁴ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 9864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (13455).

9864 is an abundant number, since it is smaller than the sum of its proper divisors (17046).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

9864 is a wasteful number, since it uses less digits than its factorization.

9864 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 149 (or 142 counting only the distinct ones).

The product of its digits is 1728, while the sum is 27.

The square root of 9864 is about 99.3176721435. The cubic root of 9864 is about 21.4462330582.

It can be divided in two parts, 986 and 4, that added together give a triangular number (990 = T₄₄).

The spelling of 9864 in words is "nine thousand, eight hundred sixty-four".