640443665280 has 512 divisors, whose sum is σ = 2159757302400. Its totient is φ = 161187102720.

The previous prime is 640443665111. The next prime is 640443665297. The reversal of 640443665280 is 82566344046.

It is a Harshad number since it is a multiple of its sum of digits (48).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 655520152 + ... + 655521128.

Almost surely, 2^640443665280 is an apocalyptic number.

640443665280 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 640443665280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1079878651200).

640443665280 is an abundant number, since it is smaller than the sum of its proper divisors (1519313637120).

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

640443665280 is a wasteful number, since it uses less digits than its factorization.

640443665280 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1282 (or 1270 counting only the distinct ones).

The product of its (nonzero) digits is 3317760, while the sum is 48.

The spelling of 640443665280 in words is "six hundred forty billion, four hundred forty-three million, six hundred sixty-five thousand, two hundred eighty".