9987 has 4 divisors (see below), whose sum is σ = 13320. Its totient is φ = 6656.

The previous prime is 9973. The next prime is 10007. The reversal of 9987 is 7899.

9987 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 7899 = 3 ⋅2633.

It is a cyclic number.

It is not a de Polignac number, because 9987 - 2⁶ = 9923 is a prime.

It is a D-number.

9987 is a lucky number.

It is a nialpdrome in base 10.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 9987.

It is not an unprimeable number, because it can be changed into a prime (9907) 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, 1662 + ... + 1667.

It is an arithmetic number, because the mean of its divisors is an integer number (3330).

2⁹⁹⁸⁷ is an apocalyptic number.

9987 is a deficient number, since it is larger than the sum of its proper divisors (3333).

9987 is a wasteful number, since it uses less digits than its factorization.

9987 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3332.

The product of its digits is 4536, while the sum is 33.

The square root of 9987 is about 99.9349788613. The cubic root of 9987 is about 21.5350069682.

The spelling of 9987 in words is "nine thousand, nine hundred eighty-seven".