6639064561 has 2 divisors, whose sum is σ = 6639064562. Its totient is φ = 6639064560.

The previous prime is 6639064547. The next prime is 6639064577. The reversal of 6639064561 is 1654609366.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 6124001536 + 515063025 = 78256^2 + 22695^2 .

It is a cyclic number.

It is not a de Polignac number, because 6639064561 - 2⁵ = 6639064529 is a prime.

It is a super-2 number, since 2×6639064561² = 88154356490252245442, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (6639064591) 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 as a sum of consecutive naturals, namely, 3319532280 + 3319532281.

It is an arithmetic number, because the mean of its divisors is an integer number (3319532281).

Almost surely, 2^6639064561 is an apocalyptic number.

It is an amenable number.

6639064561 is a deficient number, since it is larger than the sum of its proper divisors (1).

6639064561 is an equidigital number, since it uses as much as digits as its factorization.

6639064561 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 699840, while the sum is 46.

The square root of 6639064561 is about 81480.4550858671. The cubic root of 6639064561 is about 1879.4710071382.

The spelling of 6639064561 in words is "six billion, six hundred thirty-nine million, sixty-four thousand, five hundred sixty-one".