638509891387 has 2 divisors, whose sum is σ = 638509891388. Its totient is φ = 638509891386.

The previous prime is 638509891361. The next prime is 638509891447. The reversal of 638509891387 is 783198905836.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 638509891387 - 2²⁷ = 638375673659 is a prime.

It is not a weakly prime, because it can be changed into another prime (638509891337) 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, 319254945693 + 319254945694.

It is an arithmetic number, because the mean of its divisors is an integer number (319254945694).

Almost surely, 2^638509891387 is an apocalyptic number.

638509891387 is a deficient number, since it is larger than the sum of its proper divisors (1).

638509891387 is an equidigital number, since it uses as much as digits as its factorization.

638509891387 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 78382080, while the sum is 67.

The spelling of 638509891387 in words is "six hundred thirty-eight billion, five hundred nine million, eight hundred ninety-one thousand, three hundred eighty-seven".