9979 has 4 divisors (see below), whose sum is σ = 10584. Its totient is φ = 9376.

The previous prime is 9973. The next prime is 10007. The reversal of 9979 is 9799.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 9799 = 41 ⋅239.

It is a cyclic number.

It is not a de Polignac number, because 9979 - 2⁷ = 9851 is a prime.

It is a Duffinian number.

9979 is a lucky number.

It is a nialpdrome in base 11.

It is not an unprimeable number, because it can be changed into a prime (9973) 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, 277 + ... + 310.

It is an arithmetic number, because the mean of its divisors is an integer number (2646).

2⁹⁹⁷⁹ is an apocalyptic number.

9979 is a deficient number, since it is larger than the sum of its proper divisors (605).

9979 is a wasteful number, since it uses less digits than its factorization.

9979 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 604.

The product of its digits is 5103, while the sum is 34.

The square root of 9979 is about 99.8949448170. The cubic root of 9979 is about 21.5292552884.

The spelling of 9979 in words is "nine thousand, nine hundred seventy-nine".