9819921 has 4 divisors (see below), whose sum is σ = 13093232. Its totient is φ = 6546612.

The previous prime is 9819913. The next prime is 9819947. The reversal of 9819921 is 1299189.

It is a happy number.

9819921 is digitally balanced in base 2, 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 a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 9819921 - 2³ = 9819913 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 9819921.

It is not an unprimeable number, because it can be changed into a prime (9819961) 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, 1636651 + ... + 1636656.

It is an arithmetic number, because the mean of its divisors is an integer number (3273308).

Almost surely, 2^9819921 is an apocalyptic number.

It is an amenable number.

9819921 is a deficient number, since it is larger than the sum of its proper divisors (3273311).

9819921 is a wasteful number, since it uses less digits than its factorization.

9819921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3273310.

The product of its digits is 11664, while the sum is 39.

The square root of 9819921 is about 3133.6753182166. The cubic root of 9819921 is about 214.1423994737.

The spelling of 9819921 in words is "nine million, eight hundred nineteen thousand, nine hundred twenty-one".