639779863 has 2 divisors, whose sum is σ = 639779864. Its totient is φ = 639779862.

The previous prime is 639779827. The next prime is 639779869. The reversal of 639779863 is 368977936.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-639779863 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 639779798 and 639779807.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (639779869) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319889931 + 319889932.

It is an arithmetic number, because the mean of its divisors is an integer number (319889932).

Almost surely, 2^639779863 is an apocalyptic number.

639779863 is a deficient number, since it is larger than the sum of its proper divisors (1).

639779863 is an equidigital number, since it uses as much as digits as its factorization.

639779863 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 10287648, while the sum is 58.

The square root of 639779863 is about 25293.8700676666. The cubic root of 639779863 is about 861.6750582675.

The spelling of 639779863 in words is "six hundred thirty-nine million, seven hundred seventy-nine thousand, eight hundred sixty-three".