640566220800 has 288 divisors, whose sum is σ = 2310139016640. Its totient is φ = 155288371200.

The previous prime is 640566220739. The next prime is 640566220823. The reversal of 640566220800 is 8022665046.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1500039 + ... + 1879161.

It is an arithmetic number, because the mean of its divisors is an integer number (8021316030).

Almost surely, 2^640566220800 is an apocalyptic number.

640566220800 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 640566220800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1155069508320).

640566220800 is an abundant number, since it is smaller than the sum of its proper divisors (1669572795840).

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

640566220800 is a wasteful number, since it uses less digits than its factorization.

640566220800 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 379169 (or 379144 counting only the distinct ones).

The product of its (nonzero) digits is 138240, while the sum is 39.

Adding to 640566220800 its reverse (8022665046), we get a palindrome (648588885846).

The spelling of 640566220800 in words is "six hundred forty billion, five hundred sixty-six million, two hundred twenty thousand, eight hundred".