638784238447 has 4 divisors (see below), whose sum is σ = 639816200680. Its totient is φ = 637752276216.

The previous prime is 638784238427. The next prime is 638784238459. The reversal of 638784238447 is 744832487836.

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 638784238447 - 2²³ = 638775849839 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (638784238427) 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, 515980188 + ... + 515981425.

It is an arithmetic number, because the mean of its divisors is an integer number (159954050170).

Almost surely, 2^638784238447 is an apocalyptic number.

638784238447 is a deficient number, since it is larger than the sum of its proper divisors (1031962233).

638784238447 is a wasteful number, since it uses less digits than its factorization.

638784238447 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1031962232.

The product of its digits is 173408256, while the sum is 64.

The spelling of 638784238447 in words is "six hundred thirty-eight billion, seven hundred eighty-four million, two hundred thirty-eight thousand, four hundred forty-seven".