646441645640 has 128 divisors (see below), whose sum is σ = 1674981504000. Its totient is φ = 219949836288.

The previous prime is 646441645631. The next prime is 646441645693. The reversal of 646441645640 is 46546144646.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 19591076 + ... + 19624044.

It is an arithmetic number, because the mean of its divisors is an integer number (13085793000).

Almost surely, 2^646441645640 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 646441645640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (837490752000).

646441645640 is an abundant number, since it is smaller than the sum of its proper divisors (1028539858360).

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

646441645640 is a wasteful number, since it uses less digits than its factorization.

646441645640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33519 (or 33515 counting only the distinct ones).

The product of its (nonzero) digits is 6635520, while the sum is 50.

The spelling of 646441645640 in words is "six hundred forty-six billion, four hundred forty-one million, six hundred forty-five thousand, six hundred forty".