991577963520 has 704 divisors, whose sum is σ = 3722849095680. Its totient is φ = 249893683200.

The previous prime is 991577963491. The next prime is 991577963531. The reversal of 991577963520 is 25369775199.

991577963520 is a `hidden beast` number, since 9 + 9 + 1 + 577 + 9 + 6 + 3 + 52 + 0 = 666.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 184271230 + ... + 184276610.

It is an arithmetic number, because the mean of its divisors is an integer number (5288137920).

Almost surely, 2^991577963520 is an apocalyptic number.

991577963520 is a gapful number since it is divisible by the number (90) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 991577963520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1861424547840).

991577963520 is an abundant number, since it is smaller than the sum of its proper divisors (2731271132160).

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

991577963520 is a wasteful number, since it uses less digits than its factorization.

991577963520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5489 (or 5465 counting only the distinct ones).

The product of its (nonzero) digits is 32148900, while the sum is 63.

The spelling of 991577963520 in words is "nine hundred ninety-one billion, five hundred seventy-seven million, nine hundred sixty-three thousand, five hundred twenty".