640545654640 has 80 divisors (see below), whose sum is σ = 1530707599872. Its totient is φ = 249099743232.

The previous prime is 640545654631. The next prime is 640545654659. The reversal of 640545654640 is 46456545046.

640545654640 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a tau number, because it is divible by the number of its divisors (80).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3755697 + ... + 3922543.

Almost surely, 2^640545654640 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 640545654640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (765353799936).

640545654640 is an abundant number, since it is smaller than the sum of its proper divisors (890161945232).

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

640545654640 is a wasteful number, since it uses less digits than its factorization.

640545654640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 168194 (or 168188 counting only the distinct ones).

The product of its (nonzero) digits is 6912000, while the sum is 49.

The spelling of 640545654640 in words is "six hundred forty billion, five hundred forty-five million, six hundred fifty-four thousand, six hundred forty".