639216793 has 4 divisors (see below), whose sum is σ = 639435060. Its totient is φ = 638998528.

The previous prime is 639216757. The next prime is 639216827. The reversal of 639216793 is 397612936.

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

It can be written as a sum of positive squares in 2 ways, for example, as 343101529 + 296115264 = 18523^2 + 17208^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-639216793 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (639216293) 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, 104680 + ... + 110617.

It is an arithmetic number, because the mean of its divisors is an integer number (159858765).

Almost surely, 2^639216793 is an apocalyptic number.

It is an amenable number.

639216793 is a deficient number, since it is larger than the sum of its proper divisors (218267).

639216793 is a wasteful number, since it uses less digits than its factorization.

639216793 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 218266.

The product of its digits is 367416, while the sum is 46.

The square root of 639216793 is about 25282.7370551529. The cubic root of 639216793 is about 861.4221974481.

The spelling of 639216793 in words is "six hundred thirty-nine million, two hundred sixteen thousand, seven hundred ninety-three".