639418843519321 has 2 divisors, whose sum is σ = 639418843519322. Its totient is φ = 639418843519320.

The previous prime is 639418843519297. The next prime is 639418843519367. The reversal of 639418843519321 is 123915348814936.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 486429156309321 + 152989687210000 = 22055139^2 + 12368900^2 .

It is a cyclic number.

It is not a de Polignac number, because 639418843519321 - 2¹¹ = 639418843517273 is a prime.

It is not a weakly prime, because it can be changed into another prime (639418843519121) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319709421759660 + 319709421759661.

It is an arithmetic number, because the mean of its divisors is an integer number (319709421759661).

Almost surely, 2^{639418843519321} is an apocalyptic number.

It is an amenable number.

639418843519321 is a deficient number, since it is larger than the sum of its proper divisors (1).

639418843519321 is an equidigital number, since it uses as much as digits as its factorization.

639418843519321 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 134369280, while the sum is 67.

The spelling of 639418843519321 in words is "six hundred thirty-nine trillion, four hundred eighteen billion, eight hundred forty-three million, five hundred nineteen thousand, three hundred twenty-one".