639657420800 has 432 divisors, whose sum is σ = 1673983600380. Its totient is φ = 242205327360.

The previous prime is 639657420791. The next prime is 639657420821. The reversal of 639657420800 is 8024756936.

It is a happy number.

It can be written as a sum of positive squares in 6 ways, for example, as 358197462016 + 281459958784 = 598496^2 + 530528^2 .

It is a Harshad number since it is a multiple of its sum of digits (50).

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 6594406352 + ... + 6594406448.

Almost surely, 2^639657420800 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 639657420800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (836991800190).

639657420800 is an abundant number, since it is smaller than the sum of its proper divisors (1034326179580).

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

639657420800 is an equidigital number, since it uses as much as digits as its factorization.

639657420800 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 284 (or 200 counting only the distinct ones).

The product of its (nonzero) digits is 2177280, while the sum is 50.

The spelling of 639657420800 in words is "six hundred thirty-nine billion, six hundred fifty-seven million, four hundred twenty thousand, eight hundred".