640878887860 has 12 divisors (see below), whose sum is σ = 1345845664548. Its totient is φ = 256351555136.

The previous prime is 640878887849. The next prime is 640878887899. The reversal of 640878887860 is 68788878046.

It can be written as a sum of positive squares in 2 ways, for example, as 164905839396 + 475973048464 = 406086^2 + 689908^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 640878887860.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16021972177 + ... + 16021972216.

It is an arithmetic number, because the mean of its divisors is an integer number (112153805379).

Almost surely, 2^640878887860 is an apocalyptic number.

It is an amenable number.

640878887860 is an abundant number, since it is smaller than the sum of its proper divisors (704966776688).

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

640878887860 is a wasteful number, since it uses less digits than its factorization.

640878887860 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32043944402 (or 32043944400 counting only the distinct ones).

The product of its (nonzero) digits is 231211008, while the sum is 70.

The spelling of 640878887860 in words is "six hundred forty billion, eight hundred seventy-eight million, eight hundred eighty-seven thousand, eight hundred sixty".