639299856 has 80 divisors (see below), whose sum is σ = 1835993600. Its totient is φ = 190356480.

The previous prime is 639299851. The next prime is 639299879. The reversal of 639299856 is 658992936.

It is a junction number, because it is equal to n+sod(n) for n = 639299796 and 639299805.

It is not an unprimeable number, because it can be changed into a prime (639299851) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2820 + ... + 35868.

It is an arithmetic number, because the mean of its divisors is an integer number (22949920).

Almost surely, 2^639299856 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 639299856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (917996800).

639299856 is an abundant number, since it is smaller than the sum of its proper divisors (1196693744).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

639299856 is a wasteful number, since it uses less digits than its factorization.

639299856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33104 (or 33098 counting only the distinct ones).

The product of its digits is 6298560, while the sum is 57.

The square root of 639299856 is about 25284.3796839076. The cubic root of 639299856 is about 861.4595083227.

The spelling of 639299856 in words is "six hundred thirty-nine million, two hundred ninety-nine thousand, eight hundred fifty-six".