638891975297 has 4 divisors (see below), whose sum is σ = 639321628416. Its totient is φ = 638462322180.

The previous prime is 638891975257. The next prime is 638891975353. The reversal of 638891975297 is 792579198836.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 638891975297 - 2⁸ = 638891975041 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (638891975257) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 214824329 + ... + 214827302.

It is an arithmetic number, because the mean of its divisors is an integer number (159830407104).

Almost surely, 2^638891975297 is an apocalyptic number.

It is an amenable number.

638891975297 is a deficient number, since it is larger than the sum of its proper divisors (429653119).

638891975297 is a wasteful number, since it uses less digits than its factorization.

638891975297 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 429653118.

The product of its digits is 411505920, while the sum is 74.

The spelling of 638891975297 in words is "six hundred thirty-eight billion, eight hundred ninety-one million, nine hundred seventy-five thousand, two hundred ninety-seven".