640068591697920 has 3840 divisors, whose sum is σ = 3003378971443200. Its totient is φ = 125294755184640.

The previous prime is 640068591697907. The next prime is 640068591697949. The reversal of 640068591697920 is 29796195860046.

640068591697920 is a `hidden beast` number, since 6 + 4 + 0 + 0 + 6 + 8 + 591 + 6 + 9 + 7 + 9 + 20 = 666.

It is a tau number, because it is divible by the number of its divisors (3840).

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

It is an unprimeable number.

It is a polite number, since it can be written in 255 ways as a sum of consecutive naturals, for example, 721610587717 + ... + 721610588603.

It is an arithmetic number, because the mean of its divisors is an integer number (782129940480).

Almost surely, 2^{640068591697920} is an apocalyptic number.

640068591697920 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 640068591697920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1501689485721600).

640068591697920 is an abundant number, since it is smaller than the sum of its proper divisors (2363310379745280).

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

640068591697920 is a wasteful number, since it uses less digits than its factorization.

640068591697920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1189 (or 1157 counting only the distinct ones).

The product of its (nonzero) digits is 352719360, while the sum is 72.

The spelling of 640068591697920 in words is "six hundred forty trillion, sixty-eight billion, five hundred ninety-one million, six hundred ninety-seven thousand, nine hundred twenty".