639649265837 has 2 divisors, whose sum is σ = 639649265838. Its totient is φ = 639649265836.

The previous prime is 639649265833. The next prime is 639649265839. The reversal of 639649265837 is 738562946936.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 528752939716 + 110896326121 = 727154^2 + 333011^2 .

It is a cyclic number.

It is not a de Polignac number, because 639649265837 - 2² = 639649265833 is a prime.

Together with 639649265839, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (639649265833) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319824632918 + 319824632919.

It is an arithmetic number, because the mean of its divisors is an integer number (319824632919).

Almost surely, 2^639649265837 is an apocalyptic number.

It is an amenable number.

639649265837 is a deficient number, since it is larger than the sum of its proper divisors (1).

639649265837 is an equidigital number, since it uses as much as digits as its factorization.

639649265837 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 352719360, while the sum is 68.

The spelling of 639649265837 in words is "six hundred thirty-nine billion, six hundred forty-nine million, two hundred sixty-five thousand, eight hundred thirty-seven".