5643616661 has 2 divisors, whose sum is σ = 5643616662. Its totient is φ = 5643616660.

The previous prime is 5643616639. The next prime is 5643616687. The reversal of 5643616661 is 1666163465.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 5595937636 + 47679025 = 74806^2 + 6905^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-5643616661 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (5643616261) 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 as a sum of consecutive naturals, namely, 2821808330 + 2821808331.

It is an arithmetic number, because the mean of its divisors is an integer number (2821808331).

Almost surely, 2^5643616661 is an apocalyptic number.

It is an amenable number.

5643616661 is a deficient number, since it is larger than the sum of its proper divisors (1).

5643616661 is an equidigital number, since it uses as much as digits as its factorization.

5643616661 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 466560, while the sum is 44.

The square root of 5643616661 is about 75124.0085525260. The cubic root of 5643616661 is about 1780.4064910342.

The spelling of 5643616661 in words is "five billion, six hundred forty-three million, six hundred sixteen thousand, six hundred sixty-one".