639079823 has 4 divisors (see below), whose sum is σ = 645407448. Its totient is φ = 632752200.

The previous prime is 639079811. The next prime is 639079829. The reversal of 639079823 is 328970936.

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 639079823 - 2⁴ = 639079807 is a prime.

It is a super-2 number, since 2×639079823² = 816846040331422658, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (639079829) 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, 3163661 + ... + 3163862.

It is an arithmetic number, because the mean of its divisors is an integer number (161351862).

Almost surely, 2^639079823 is an apocalyptic number.

639079823 is a deficient number, since it is larger than the sum of its proper divisors (6327625).

639079823 is a wasteful number, since it uses less digits than its factorization.

639079823 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6327624.

The product of its (nonzero) digits is 489888, while the sum is 47.

The square root of 639079823 is about 25280.0281447628. The cubic root of 639079823 is about 861.3606651541.

The spelling of 639079823 in words is "six hundred thirty-nine million, seventy-nine thousand, eight hundred twenty-three".