638491479643 has 2 divisors, whose sum is σ = 638491479644. Its totient is φ = 638491479642.

The previous prime is 638491479583. The next prime is 638491479739. The reversal of 638491479643 is 346974194836.

638491479643 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 638491479643 - 2¹³ = 638491471451 is a prime.

It is not a weakly prime, because it can be changed into another prime (638494479643) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319245739821 + 319245739822.

It is an arithmetic number, because the mean of its divisors is an integer number (319245739822).

Almost surely, 2^638491479643 is an apocalyptic number.

638491479643 is a deficient number, since it is larger than the sum of its proper divisors (1).

638491479643 is an equidigital number, since it uses as much as digits as its factorization.

638491479643 is an evil number, because the sum of its binary digits is even.

The product of its digits is 94058496, while the sum is 64.

The spelling of 638491479643 in words is "six hundred thirty-eight billion, four hundred ninety-one million, four hundred seventy-nine thousand, six hundred forty-three".