639942976 has 56 divisors (see below), whose sum is σ = 1313809920. Its totient is φ = 309084672.

The previous prime is 639942973. The next prime is 639942977. The reversal of 639942976 is 679249936.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (639942973) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 236286 + ... + 238978.

Almost surely, 2^639942976 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 639942976, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (656904960).

639942976 is an abundant number, since it is smaller than the sum of its proper divisors (673866944).

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

639942976 is a wasteful number, since it uses less digits than its factorization.

639942976 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2831 (or 2821 counting only the distinct ones).

The product of its digits is 4408992, while the sum is 55.

The square root of 639942976 is about 25297.0942204831. The cubic root of 639942976 is about 861.7482805684.

The spelling of 639942976 in words is "six hundred thirty-nine million, nine hundred forty-two thousand, nine hundred seventy-six".