9991978323723 has 48 divisors (see below), whose sum is σ = 16330930027776. Its totient is φ = 6054687908640.

The previous prime is 9991978323713. The next prime is 9991978323727. The reversal of 9991978323723 is 3273238791999.

9991978323723 is a `hidden beast` number, since 9 + 9 + 91 + 97 + 83 + 2 + 372 + 3 = 666.

It is not a de Polignac number, because 9991978323723 - 2⁴ = 9991978323707 is a prime.

It is not an unprimeable number, because it can be changed into a prime (9991978323727) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 15134761 + ... + 15781157.

It is an arithmetic number, because the mean of its divisors is an integer number (340227708912).

Almost surely, 2^{9991978323723} is an apocalyptic number.

9991978323723 is a deficient number, since it is larger than the sum of its proper divisors (6338951704053).

9991978323723 is a wasteful number, since it uses less digits than its factorization.

9991978323723 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 652206 (or 652194 counting only the distinct ones).

The product of its digits is 277766496, while the sum is 72.

The spelling of 9991978323723 in words is "nine trillion, nine hundred ninety-one billion, nine hundred seventy-eight million, three hundred twenty-three thousand, seven hundred twenty-three".