638913673 has 2 divisors, whose sum is σ = 638913674. Its totient is φ = 638913672.

The previous prime is 638913661. The next prime is 638913679. The reversal of 638913673 is 376319836.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 545829769 + 93083904 = 23363^2 + 9648^2 .

It is a cyclic number.

It is not a de Polignac number, because 638913673 - 2⁵ = 638913641 is a prime.

It is not a weakly prime, because it can be changed into another prime (638913679) 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, 319456836 + 319456837.

It is an arithmetic number, because the mean of its divisors is an integer number (319456837).

Almost surely, 2^638913673 is an apocalyptic number.

It is an amenable number.

638913673 is a deficient number, since it is larger than the sum of its proper divisors (1).

638913673 is an equidigital number, since it uses as much as digits as its factorization.

638913673 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 489888, while the sum is 46.

The square root of 638913673 is about 25276.7417401848. The cubic root of 638913673 is about 861.2860122580.

The spelling of 638913673 in words is "six hundred thirty-eight million, nine hundred thirteen thousand, six hundred seventy-three".