990683799561 has 9 divisors (see below), whose sum is σ = 1430992023591. Its totient is φ = 660453875712.

The previous prime is 990683799509. The next prime is 990683799667. The reversal of 990683799561 is 165997386099.

The square root of 990683799561 is 995331.

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

It can be written as a sum of positive squares in only one way, i.e., 990671855625 + 11943936 = 995325^2 + 3456^2 .

It is a tau number, because it is divible by the number of its divisors (9).

It is not a de Polignac number, because 990683799561 - 2¹¹ = 990683797513 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 990683799561.

It is not an unprimeable number, because it can be changed into a prime (990683795561) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 2820105 + ... + 3151881.

Almost surely, 2^990683799561 is an apocalyptic number.

990683799561 is the 995331-st square number.

990683799561 is the 497666-th centered octagonal number.

It is an amenable number.

990683799561 is a deficient number, since it is larger than the sum of its proper divisors (440308224030).

990683799561 is an frugal number, since it uses more digits than its factorization.

990683799561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 663560 (or 331780 counting only the distinct ones).

The product of its (nonzero) digits is 198404640, while the sum is 72.

It can be divided in two parts, 990683 and 799561, that added together give a square (1790244 = 1338²).

The spelling of 990683799561 in words is "nine hundred ninety billion, six hundred eighty-three million, seven hundred ninety-nine thousand, five hundred sixty-one".