9979821 has 16 divisors (see below), whose sum is σ = 14920320. Its totient is φ = 6592320.

The previous prime is 9979819. The next prime is 9979843. The reversal of 9979821 is 1289799.

9979821 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 9979821 - 2¹ = 9979819 is a prime.

It is an Ulam number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9979811) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1416 + ... + 4686.

It is an arithmetic number, because the mean of its divisors is an integer number (932520).

Almost surely, 2^9979821 is an apocalyptic number.

It is an amenable number.

9979821 is a deficient number, since it is larger than the sum of its proper divisors (4940499).

9979821 is a wasteful number, since it uses less digits than its factorization.

9979821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3393 (or 3387 counting only the distinct ones).

The product of its digits is 81648, while the sum is 45.

The square root of 9979821 is about 3159.0854689293. The cubic root of 9979821 is about 215.2984569608.

The spelling of 9979821 in words is "nine million, nine hundred seventy-nine thousand, eight hundred twenty-one".