640778289648 has 240 divisors, whose sum is σ = 1994959171584. Its totient is φ = 176528540160.

The previous prime is 640778289553. The next prime is 640778289691. The reversal of 640778289648 is 846982877046.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 20180761 + ... + 20212487.

Almost surely, 2^640778289648 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 640778289648, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (997479585792).

640778289648 is an abundant number, since it is smaller than the sum of its proper divisors (1354180881936).

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

640778289648 is a wasteful number, since it uses less digits than its factorization.

640778289648 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32060 (or 32047 counting only the distinct ones).

The product of its (nonzero) digits is 260112384, while the sum is 69.

The spelling of 640778289648 in words is "six hundred forty billion, seven hundred seventy-eight million, two hundred eighty-nine thousand, six hundred forty-eight".