9888372721 has 4 divisors (see below), whose sum is σ = 9892191744. Its totient is φ = 9884553700.

The previous prime is 9888372719. The next prime is 9888372737. The reversal of 9888372721 is 1272738889.

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 9888372721 - 2¹ = 9888372719 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (9888376721) 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, 1905625 + ... + 1910806.

It is an arithmetic number, because the mean of its divisors is an integer number (2473047936).

Almost surely, 2^9888372721 is an apocalyptic number.

It is an amenable number.

9888372721 is a deficient number, since it is larger than the sum of its proper divisors (3819023).

9888372721 is a wasteful number, since it uses less digits than its factorization.

9888372721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3819022.

The product of its digits is 2709504, while the sum is 55.

The square root of 9888372721 is about 99440.2972692660. The cubic root of 9888372721 is about 2146.3882190816.

The spelling of 9888372721 in words is "nine billion, eight hundred eighty-eight million, three hundred seventy-two thousand, seven hundred twenty-one".