10391559721 has 3 divisors (see below), whose sum is σ = 10391661661. Its totient is φ = 10391457782.

The previous prime is 10391559719. The next prime is 10391559727. The reversal of 10391559721 is 12795519301.

The square root of 10391559721 is 101939.

It is a perfect power (a square), and thus also a powerful number.

10391559721 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, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 12795519301 = 2833 ⋅4516597.

It is not a de Polignac number, because 10391559721 - 2¹ = 10391559719 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (10391559727) 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 2 ways as a sum of consecutive naturals, for example, 50970 + ... + 152908.

Almost surely, 2^10391559721 is an apocalyptic number.

10391559721 is the 101939-th square number.

10391559721 is the 50970-th centered octagonal number.

It is an amenable number.

10391559721 is a deficient number, since it is larger than the sum of its proper divisors (101940).

10391559721 is an frugal number, since it uses more digits than its factorization.

10391559721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 203878 (or 101939 counting only the distinct ones).

The product of its (nonzero) digits is 85050, while the sum is 43.

The spelling of 10391559721 in words is "ten billion, three hundred ninety-one million, five hundred fifty-nine thousand, seven hundred twenty-one".