640868159520 has 384 divisors, whose sum is σ = 2302147008000. Its totient is φ = 166410731520.

The previous prime is 640868159513. The next prime is 640868159539. The reversal of 640868159520 is 25951868046.

640868159520 is a `hidden beast` number, since 6 + 4 + 0 + 8 + 68 + 1 + 59 + 520 = 666.

It is a Harshad number since it is a multiple of its sum of digits (54).

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, 100778101 + ... + 100784459.

It is an arithmetic number, because the mean of its divisors is an integer number (5995174500).

Almost surely, 2^640868159520 is an apocalyptic number.

640868159520 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 640868159520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1151073504000).

640868159520 is an abundant number, since it is smaller than the sum of its proper divisors (1661278848480).

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

640868159520 is a wasteful number, since it uses less digits than its factorization.

640868159520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6993 (or 6979 counting only the distinct ones).

The product of its (nonzero) digits is 4147200, while the sum is 54.

The spelling of 640868159520 in words is "six hundred forty billion, eight hundred sixty-eight million, one hundred fifty-nine thousand, five hundred twenty".