991172287528 has 16 divisors (see below), whose sum is σ = 1863624780000. Its totient is φ = 494205679536.

The previous prime is 991172287517. The next prime is 991172287529. The reversal of 991172287528 is 825782271199.

991172287528 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not an unprimeable number, because it can be changed into a prime (991172287529) 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, 172554978 + ... + 172560721.

It is an arithmetic number, because the mean of its divisors is an integer number (116476548750).

Almost surely, 2^991172287528 is an apocalyptic number.

It is an amenable number.

991172287528 is a deficient number, since it is larger than the sum of its proper divisors (872452492472).

991172287528 is a wasteful number, since it uses less digits than its factorization.

991172287528 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 345116064 (or 345116060 counting only the distinct ones).

The product of its digits is 10160640, while the sum is 61.

The spelling of 991172287528 in words is "nine hundred ninety-one billion, one hundred seventy-two million, two hundred eighty-seven thousand, five hundred twenty-eight".