639815244 has 24 divisors (see below), whose sum is σ = 1494071040. Its totient is φ = 213104784.

The previous prime is 639815191. The next prime is 639815249. The reversal of 639815244 is 442518936.

It is a junction number, because it is equal to n+sod(n) for n = 639815196 and 639815205.

It is not an unprimeable number, because it can be changed into a prime (639815249) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4384 + ... + 36039.

It is an arithmetic number, because the mean of its divisors is an integer number (62252960).

Almost surely, 2^639815244 is an apocalyptic number.

It is an amenable number.

639815244 is an abundant number, since it is smaller than the sum of its proper divisors (854255796).

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

639815244 is a wasteful number, since it uses less digits than its factorization.

639815244 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 41749 (or 41747 counting only the distinct ones).

The product of its digits is 207360, while the sum is 42.

The square root of 639815244 is about 25294.5694567035. The cubic root of 639815244 is about 861.6909420452.

The spelling of 639815244 in words is "six hundred thirty-nine million, eight hundred fifteen thousand, two hundred forty-four".