5557999566681 has 45 divisors (see below), whose sum is σ = 8511466706413. Its totient is φ = 3614393257920.

The previous prime is 5557999566619. The next prime is 5557999566719. The reversal of 5557999566681 is 1866659997555.

It is a happy number.

The square root of 5557999566681 is 2357541.

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 5149908574281 + 408090992400 = 2269341^2 + 638820^2 .

It is not a de Polignac number, because 5557999566681 - 2⁹ = 5557999566169 is a prime.

It is a super-2 number, since 2×5557999566681² (a number of 26 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (81).

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 5557999566681.

It is not an unprimeable number, because it can be changed into a prime (5557999586681) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 44 ways as a sum of consecutive naturals, for example, 869929435 + ... + 869935823.

Almost surely, 2^{5557999566681} is an apocalyptic number.

5557999566681 is the 2357541-st square number.

5557999566681 is the 1178771-st centered octagonal number.

It is an amenable number.

5557999566681 is a deficient number, since it is larger than the sum of its proper divisors (2953467139732).

5557999566681 is an frugal number, since it uses more digits than its factorization.

5557999566681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12872 (or 6433 counting only the distinct ones).

The product of its digits is 5511240000, while the sum is 81.

Multiplying 5557999566681 by its sum of digits (81), we get a square (450197964901161 = 21217869²).

5557999566681 divided by its sum of digits (81) gives a square (68617278601 = 261949²).

The spelling of 5557999566681 in words is "five trillion, five hundred fifty-seven billion, nine hundred ninety-nine million, five hundred sixty-six thousand, six hundred eighty-one".