9819721 has 4 divisors (see below), whose sum is σ = 9966352. Its totient is φ = 9673092.

The previous prime is 9819707. The next prime is 9819731. The reversal of 9819721 is 1279189.

9819721 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 a cyclic number.

It is not a de Polignac number, because 9819721 - 2¹¹ = 9817673 is a prime.

It is a Duffinian number.

9819721 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (9819731) 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, 73215 + ... + 73348.

It is an arithmetic number, because the mean of its divisors is an integer number (2491588).

Almost surely, 2^9819721 is an apocalyptic number.

It is an amenable number.

9819721 is a deficient number, since it is larger than the sum of its proper divisors (146631).

9819721 is a wasteful number, since it uses less digits than its factorization.

9819721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 146630.

The product of its digits is 9072, while the sum is 37.

The square root of 9819721 is about 3133.6434066435. The cubic root of 9819721 is about 214.1409456680.

The spelling of 9819721 in words is "nine million, eight hundred nineteen thousand, seven hundred twenty-one".