640520317774820 has 192 divisors, whose sum is σ = 1672134019766784. Its totient is φ = 201046465290240.

The previous prime is 640520317774817. The next prime is 640520317774847. The reversal of 640520317774820 is 28477713025046.

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, 314327267 + ... + 316358453.

It is an arithmetic number, because the mean of its divisors is an integer number (8709031352952).

Almost surely, 2^{640520317774820} 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 640520317774820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (836067009883392).

640520317774820 is an abundant number, since it is smaller than the sum of its proper divisors (1031613701991964).

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

640520317774820 is a wasteful number, since it uses less digits than its factorization.

640520317774820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2034838 (or 2034836 counting only the distinct ones).

The product of its (nonzero) digits is 15805440, while the sum is 56.

The spelling of 640520317774820 in words is "six hundred forty trillion, five hundred twenty billion, three hundred seventeen million, seven hundred seventy-four thousand, eight hundred twenty".