9729721 has 4 divisors (see below), whose sum is σ = 9743332. Its totient is φ = 9716112.

The previous prime is 9729697. The next prime is 9729743. The reversal of 9729721 is 1279279.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1279279 = 83 ⋅15413.

It can be written as a sum of positive squares in 2 ways, for example, as 4141225 + 5588496 = 2035^2 + 2364^2 .

It is a cyclic number.

It is not a de Polignac number, because 9729721 - 2¹³ = 9721529 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (9729791) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5670 + ... + 7183.

It is an arithmetic number, because the mean of its divisors is an integer number (2435833).

Almost surely, 2^9729721 is an apocalyptic number.

It is an amenable number.

9729721 is a deficient number, since it is larger than the sum of its proper divisors (13611).

9729721 is a wasteful number, since it uses less digits than its factorization.

9729721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13610.

The product of its digits is 15876, while the sum is 37.

The square root of 9729721 is about 3119.2500701290. The cubic root of 9729721 is about 213.4847197499.

The spelling of 9729721 in words is "nine million, seven hundred twenty-nine thousand, seven hundred twenty-one".