638994834437 has 2 divisors, whose sum is σ = 638994834438. Its totient is φ = 638994834436.

The previous prime is 638994834427. The next prime is 638994834503. The reversal of 638994834437 is 734438499836.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 355375745956 + 283619088481 = 596134^2 + 532559^2 .

It is a cyclic number.

It is not a de Polignac number, because 638994834437 - 2¹⁶ = 638994768901 is a prime.

It is a super-2 number, since 2×638994834437² (a number of 24 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (638994834427) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319497417218 + 319497417219.

It is an arithmetic number, because the mean of its divisors is an integer number (319497417219).

Almost surely, 2^638994834437 is an apocalyptic number.

It is an amenable number.

638994834437 is a deficient number, since it is larger than the sum of its proper divisors (1).

638994834437 is an equidigital number, since it uses as much as digits as its factorization.

638994834437 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 376233984, while the sum is 68.

The spelling of 638994834437 in words is "six hundred thirty-eight billion, nine hundred ninety-four million, eight hundred thirty-four thousand, four hundred thirty-seven".