991172878176 has 96 divisors (see below), whose sum is σ = 2802172974048. Its totient is φ = 304954122240.

The previous prime is 991172878139. The next prime is 991172878247. The reversal of 991172878176 is 671878271199.

991172878176 is digitally balanced in base 2 and base 4, because in such bases it contains all the possibile digits an equal number of times.

It is a tau number, because it is divible by the number of its divisors (96).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 28333336 + ... + 28368296.

It is an arithmetic number, because the mean of its divisors is an integer number (29189301813).

Almost surely, 2^991172878176 is an apocalyptic number.

991172878176 is a gapful number since it is divisible by the number (96) formed by its first and last digit.

It is an amenable number.

991172878176 is an abundant number, since it is smaller than the sum of its proper divisors (1811000095872).

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

991172878176 is a wasteful number, since it uses less digits than its factorization.

991172878176 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 57704 (or 57696 counting only the distinct ones).

The product of its digits is 21337344, while the sum is 66.

The spelling of 991172878176 in words is "nine hundred ninety-one billion, one hundred seventy-two million, eight hundred seventy-eight thousand, one hundred seventy-six".