638620370257 has 4 divisors (see below), whose sum is σ = 638633313136. Its totient is φ = 638607427380.

The previous prime is 638620370251. The next prime is 638620370281. The reversal of 638620370257 is 752073026836.

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 638620370257 - 2³⁹ = 88864556369 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 638620370257.

It is not an unprimeable number, because it can be changed into a prime (638620370251) 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, 6397143 + ... + 6496204.

It is an arithmetic number, because the mean of its divisors is an integer number (159658328284).

Almost surely, 2^638620370257 is an apocalyptic number.

It is an amenable number.

638620370257 is a deficient number, since it is larger than the sum of its proper divisors (12942879).

638620370257 is a wasteful number, since it uses less digits than its factorization.

638620370257 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12942878.

The product of its (nonzero) digits is 2540160, while the sum is 49.

The spelling of 638620370257 in words is "six hundred thirty-eight billion, six hundred twenty million, three hundred seventy thousand, two hundred fifty-seven".