638005321 has 2 divisors, whose sum is σ = 638005322. Its totient is φ = 638005320.

The previous prime is 638005267. The next prime is 638005391. The reversal of 638005321 is 123500836.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 405015625 + 232989696 = 20125^2 + 15264^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-638005321 is a prime.

It is a super-3 number, since 3×638005321³ (a number of 27 digits) contains 333 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 638005321.

It is not a weakly prime, because it can be changed into another prime (638005391) 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, 319002660 + 319002661.

It is an arithmetic number, because the mean of its divisors is an integer number (319002661).

Almost surely, 2^638005321 is an apocalyptic number.

It is an amenable number.

638005321 is a deficient number, since it is larger than the sum of its proper divisors (1).

638005321 is an equidigital number, since it uses as much as digits as its factorization.

638005321 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4320, while the sum is 28.

The square root of 638005321 is about 25258.7672106142. The cubic root of 638005321 is about 860.8776514432.

The spelling of 638005321 in words is "six hundred thirty-eight million, five thousand, three hundred twenty-one".