639046561 has 2 divisors, whose sum is σ = 639046562. Its totient is φ = 639046560.

The previous prime is 639046487. The next prime is 639046567. The reversal of 639046561 is 165640936.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 334194961 + 304851600 = 18281^2 + 17460^2 .

It is a cyclic number.

It is not a de Polignac number, because 639046561 - 2¹⁹ = 638522273 is a prime.

It is not a weakly prime, because it can be changed into another prime (639046567) 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, 319523280 + 319523281.

It is an arithmetic number, because the mean of its divisors is an integer number (319523281).

Almost surely, 2^639046561 is an apocalyptic number.

It is an amenable number.

639046561 is a deficient number, since it is larger than the sum of its proper divisors (1).

639046561 is an equidigital number, since it uses as much as digits as its factorization.

639046561 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 116640, while the sum is 40.

The square root of 639046561 is about 25279.3702650996. The cubic root of 639046561 is about 861.3457212329.

The spelling of 639046561 in words is "six hundred thirty-nine million, forty-six thousand, five hundred sixty-one".