638681308063 has 4 divisors (see below), whose sum is σ = 638721918808. Its totient is φ = 638640697320.

The previous prime is 638681308061. The next prime is 638681308073. The reversal of 638681308063 is 360803186836.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 638681308063 - 2¹ = 638681308061 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 638681308063.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (638681308061) 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, 20281773 + ... + 20313238.

It is an arithmetic number, because the mean of its divisors is an integer number (159680479702).

Almost surely, 2^638681308063 is an apocalyptic number.

638681308063 is a deficient number, since it is larger than the sum of its proper divisors (40610745).

638681308063 is a wasteful number, since it uses less digits than its factorization.

638681308063 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40610744.

The product of its (nonzero) digits is 2985984, while the sum is 52.

The spelling of 638681308063 in words is "six hundred thirty-eight billion, six hundred eighty-one million, three hundred eight thousand, sixty-three".