638647393 has 2 divisors, whose sum is σ = 638647394. Its totient is φ = 638647392.

The previous prime is 638647333. The next prime is 638647397. The reversal of 638647393 is 393746836.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 564205009 + 74442384 = 23753^2 + 8628^2 .

It is a cyclic number.

It is not a de Polignac number, because 638647393 - 2¹⁷ = 638516321 is a prime.

It is not a weakly prime, because it can be changed into another prime (638647397) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319323696 + 319323697.

It is an arithmetic number, because the mean of its divisors is an integer number (319323697).

Almost surely, 2^638647393 is an apocalyptic number.

It is an amenable number.

638647393 is a deficient number, since it is larger than the sum of its proper divisors (1).

638647393 is an equidigital number, since it uses as much as digits as its factorization.

638647393 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1959552, while the sum is 49.

The square root of 638647393 is about 25271.4738984492. The cubic root of 638647393 is about 861.1663429310.

The spelling of 638647393 in words is "six hundred thirty-eight million, six hundred forty-seven thousand, three hundred ninety-three".