9931539539861 has 4 divisors (see below), whose sum is σ = 9935916597900. Its totient is φ = 9927162481824.

The previous prime is 9931539539813. The next prime is 9931539539869. The reversal of 9931539539861 is 1689359351399.

9931539539861 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 301751363761 + 9629788176100 = 549319^2 + 3103190^2 .

It is a cyclic number.

It is not a de Polignac number, because 9931539539861 - 2¹⁸ = 9931539277717 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9931539539869) 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, 2188525616 + ... + 2188530153.

It is an arithmetic number, because the mean of its divisors is an integer number (2483979149475).

Almost surely, 2^{9931539539861} is an apocalyptic number.

It is an amenable number.

9931539539861 is a deficient number, since it is larger than the sum of its proper divisors (4377058039).

9931539539861 is a wasteful number, since it uses less digits than its factorization.

9931539539861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4377058038.

The product of its digits is 212576400, while the sum is 71.

The spelling of 9931539539861 in words is "nine trillion, nine hundred thirty-one billion, five hundred thirty-nine million, five hundred thirty-nine thousand, eight hundred sixty-one".