643684597920 has 576 divisors, whose sum is σ = 2706604153344. Its totient is φ = 135653253120.

The previous prime is 643684597861. The next prime is 643684597921. The reversal of 643684597920 is 29795486346.

643684597920 is a `hidden beast` number, since 6 + 4 + 36 + 8 + 4 + 597 + 9 + 2 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (63).

It is not an unprimeable number, because it can be changed into a prime (643684597921) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 139293210 + ... + 139297830.

It is an arithmetic number, because the mean of its divisors is an integer number (4698965544).

Almost surely, 2^643684597920 is an apocalyptic number.

643684597920 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 643684597920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1353302076672).

643684597920 is an abundant number, since it is smaller than the sum of its proper divisors (2062919555424).

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

643684597920 is a wasteful number, since it uses less digits than its factorization.

643684597920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5725 (or 5714 counting only the distinct ones).

The product of its (nonzero) digits is 78382080, while the sum is 63.

The spelling of 643684597920 in words is "six hundred forty-three billion, six hundred eighty-four million, five hundred ninety-seven thousand, nine hundred twenty".