9728786521 has 8 divisors (see below), whose sum is σ = 9767615624. Its totient is φ = 9689984640.

The previous prime is 9728786497. The next prime is 9728786527. The reversal of 9728786521 is 1256878279.

It can be written as a sum of positive squares in 4 ways, for example, as 2079360000 + 7649426521 = 45600^2 + 87461^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 9728786521 - 2¹⁹ = 9728262233 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (9728786527) 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 7 ways as a sum of consecutive naturals, for example, 995941 + ... + 1005661.

It is an arithmetic number, because the mean of its divisors is an integer number (1220951953).

Almost surely, 2^9728786521 is an apocalyptic number.

It is an amenable number.

9728786521 is a deficient number, since it is larger than the sum of its proper divisors (38829103).

9728786521 is a wasteful number, since it uses less digits than its factorization.

9728786521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13611.

The product of its digits is 3386880, while the sum is 55.

The square root of 9728786521 is about 98634.6111717383. The cubic root of 9728786521 is about 2134.7788490591.

The spelling of 9728786521 in words is "nine billion, seven hundred twenty-eight million, seven hundred eighty-six thousand, five hundred twenty-one".