639938972640 has 288 divisors, whose sum is σ = 2332343583360. Its totient is φ = 146971376640.

The previous prime is 639938972611. The next prime is 639938972663. The reversal of 639938972640 is 46279839936.

It is a Harshad number since it is a multiple of its sum of digits (66).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 813567 + ... + 1393473.

It is an arithmetic number, because the mean of its divisors is an integer number (8098415220).

Almost surely, 2^639938972640 is an apocalyptic number.

639938972640 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 639938972640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1166171791680).

639938972640 is an abundant number, since it is smaller than the sum of its proper divisors (1692404610720).

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

639938972640 is a wasteful number, since it uses less digits than its factorization.

639938972640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 579966 (or 579947 counting only the distinct ones).

The product of its (nonzero) digits is 105815808, while the sum is 66.

The spelling of 639938972640 in words is "six hundred thirty-nine billion, nine hundred thirty-eight million, nine hundred seventy-two thousand, six hundred forty".