991697305600 has 171 divisors, whose sum is σ = 2465743256767. Its totient is φ = 395659182080.

The previous prime is 991697305541. The next prime is 991697305603. The reversal of 991697305600 is 6503796199.

The square root of 991697305600 is 995840.

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

It can be written as a sum of positive squares in 4 ways, for example, as 164848992256 + 826848313344 = 406016^2 + 909312^2 .

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (991697305603) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 2549350206 + ... + 2549350594.

Almost surely, 2^991697305600 is an apocalyptic number.

991697305600 is the 995840-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 991697305600

991697305600 is an abundant number, since it is smaller than the sum of its proper divisors (1474045951167).

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

991697305600 is an frugal number, since it uses more digits than its factorization.

991697305600 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 824 (or 396 counting only the distinct ones).

The product of its (nonzero) digits is 2755620, while the sum is 55.

The spelling of 991697305600 in words is "nine hundred ninety-one billion, six hundred ninety-seven million, three hundred five thousand, six hundred".