640934386073856 has 864 divisors, whose sum is σ = 2277576677376000. Its totient is φ = 177088215306240.

The previous prime is 640934386073843. The next prime is 640934386073881. The reversal of 640934386073856 is 658370683439046.

640934386073856 is a `hidden beast` number, since 6 + 4 + 0 + 9 + 3 + 4 + 3 + 8 + 607 + 3 + 8 + 5 + 6 = 666.

It is a tau number, because it is divible by the number of its divisors (864).

It is a Harshad number since it is a multiple of its sum of digits (72).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 14940522295 + ... + 14940565193.

Almost surely, 2^{640934386073856} 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 640934386073856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1138788338688000).

640934386073856 is an abundant number, since it is smaller than the sum of its proper divisors (1636642291302144).

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

640934386073856 is a wasteful number, since it uses less digits than its factorization.

640934386073856 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 44392 (or 44365 counting only the distinct ones).

The product of its (nonzero) digits is 1881169920, while the sum is 72.

The spelling of 640934386073856 in words is "six hundred forty trillion, nine hundred thirty-four billion, three hundred eighty-six million, seventy-three thousand, eight hundred fifty-six".