638396478197 has 2 divisors, whose sum is σ = 638396478198. Its totient is φ = 638396478196.

The previous prime is 638396478143. The next prime is 638396478259. The reversal of 638396478197 is 791874693836.

638396478197 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 can be written as a sum of positive squares in only one way, i.e., 626146194436 + 12250283761 = 791294^2 + 110681^2 .

It is a cyclic number.

It is not a de Polignac number, because 638396478197 - 2³⁶ = 569677001461 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 638396478197.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (638396478997) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319198239098 + 319198239099.

It is an arithmetic number, because the mean of its divisors is an integer number (319198239099).

Almost surely, 2^638396478197 is an apocalyptic number.

It is an amenable number.

638396478197 is a deficient number, since it is larger than the sum of its proper divisors (1).

638396478197 is an equidigital number, since it uses as much as digits as its factorization.

638396478197 is an evil number, because the sum of its binary digits is even.

The product of its digits is 329204736, while the sum is 71.

The spelling of 638396478197 in words is "six hundred thirty-eight billion, three hundred ninety-six million, four hundred seventy-eight thousand, one hundred ninety-seven".