639430909687 has 2 divisors, whose sum is σ = 639430909688. Its totient is φ = 639430909686.

The previous prime is 639430909681. The next prime is 639430909801. The reversal of 639430909687 is 786909034936.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 639430909687 - 2³ = 639430909679 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (639430909681) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319715454843 + 319715454844.

It is an arithmetic number, because the mean of its divisors is an integer number (319715454844).

Almost surely, 2^639430909687 is an apocalyptic number.

639430909687 is a deficient number, since it is larger than the sum of its proper divisors (1).

639430909687 is an equidigital number, since it uses as much as digits as its factorization.

639430909687 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 52907904, while the sum is 64.

The spelling of 639430909687 in words is "six hundred thirty-nine billion, four hundred thirty million, nine hundred nine thousand, six hundred eighty-seven".