640636320500 has 96 divisors (see below), whose sum is σ = 1531859067648. Its totient is φ = 232117104000.

The previous prime is 640636320481. The next prime is 640636320503. The reversal of 640636320500 is 5023636046.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640636320503) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1313249 + ... + 1733751.

It is an arithmetic number, because the mean of its divisors is an integer number (15956865288).

Almost surely, 2^640636320500 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 640636320500, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (765929533824).

640636320500 is an abundant number, since it is smaller than the sum of its proper divisors (891222747148).

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

640636320500 is a wasteful number, since it uses less digits than its factorization.

640636320500 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 420810 (or 420798 counting only the distinct ones).

The product of its (nonzero) digits is 77760, while the sum is 35.

Adding to 640636320500 its reverse (5023636046), we get a palindrome (645659956546).

The spelling of 640636320500 in words is "six hundred forty billion, six hundred thirty-six million, three hundred twenty thousand, five hundred".