9861031891984 has 135 divisors (see below), whose sum is σ = 24068974097277. Its totient is φ = 3900615368832.

The previous prime is 9861031891981. The next prime is 9861031892009. The reversal of 9861031891984 is 4891981301689.

The square root of 9861031891984 is 3140228.

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

9861031891984 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in only one way, i.e., 1458732528400 + 8402299363584 = 1207780^2 + 2898672^2 .

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (9861031891981) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 1143038679 + ... + 1143047305.

Almost surely, 2^{9861031891984} is an apocalyptic number.

9861031891984 is the 3140228-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 9861031891984

9861031891984 is an abundant number, since it is smaller than the sum of its proper divisors (14207942205293).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

9861031891984 is an frugal number, since it uses more digits than its factorization.

9861031891984 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17302 (or 8649 counting only the distinct ones).

The product of its (nonzero) digits is 26873856, while the sum is 67.

The spelling of 9861031891984 in words is "nine trillion, eight hundred sixty-one billion, thirty-one million, eight hundred ninety-one thousand, nine hundred eighty-four".