638707065657 has 4 divisors (see below), whose sum is σ = 851609420880. Its totient is φ = 425804710436.

The previous prime is 638707065643. The next prime is 638707065673. The reversal of 638707065657 is 756560707836.

638707065657 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 638707065657 - 2⁴ = 638707065641 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 638707065657.

It is not an unprimeable number, because it can be changed into a prime (638707065697) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 106451177607 + ... + 106451177612.

It is an arithmetic number, because the mean of its divisors is an integer number (212902355220).

Almost surely, 2^638707065657 is an apocalyptic number.

It is an amenable number.

638707065657 is a deficient number, since it is larger than the sum of its proper divisors (212902355223).

638707065657 is a wasteful number, since it uses less digits than its factorization.

638707065657 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 212902355222.

The product of its (nonzero) digits is 44452800, while the sum is 60.

The spelling of 638707065657 in words is "six hundred thirty-eight billion, seven hundred seven million, sixty-five thousand, six hundred fifty-seven".