9993688721 has 4 divisors (see below), whose sum is σ = 10066635492. Its totient is φ = 9920741952.

The previous prime is 9993688687. The next prime is 9993688729. The reversal of 9993688721 is 1278863999.

9993688721 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.

It can be written as a sum of positive squares in 2 ways, for example, as 3170928721 + 6822760000 = 56311^2 + 82600^2 .

It is a cyclic number.

It is not a de Polignac number, because 9993688721 - 2⁶ = 9993688657 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (9993688729) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 36473180 + ... + 36473453.

It is an arithmetic number, because the mean of its divisors is an integer number (2516658873).

Almost surely, 2^9993688721 is an apocalyptic number.

It is an amenable number.

9993688721 is a deficient number, since it is larger than the sum of its proper divisors (72946771).

9993688721 is a wasteful number, since it uses less digits than its factorization.

9993688721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 72946770.

The product of its digits is 11757312, while the sum is 62.

The square root of 9993688721 is about 99968.4386243979. The cubic root of 9993688721 is about 2153.9813533668.

The spelling of 9993688721 in words is "nine billion, nine hundred ninety-three million, six hundred eighty-eight thousand, seven hundred twenty-one".