9721239 has 16 divisors (see below), whose sum is σ = 14214144. Its totient is φ = 5860800.

The previous prime is 9721199. The next prime is 9721241. The reversal of 9721239 is 9321279.

9721239 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 9721239 - 2⁹ = 9720727 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9721039) 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, 6699 + ... + 8019.

It is an arithmetic number, because the mean of its divisors is an integer number (888384).

Almost surely, 2^9721239 is an apocalyptic number.

9721239 is a deficient number, since it is larger than the sum of its proper divisors (4492905).

9721239 is a wasteful number, since it uses less digits than its factorization.

9721239 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1558.

The product of its digits is 6804, while the sum is 33.

The square root of 9721239 is about 3117.8901520098. The cubic root of 9721239 is about 213.4226657665.

It can be divided in two parts, 972 and 1239, that added together give a triangular number (2211 = T₆₆).

The spelling of 9721239 in words is "nine million, seven hundred twenty-one thousand, two hundred thirty-nine".