643651660800 has 1980 divisors, whose sum is σ = 2744837611560. Its totient is φ = 148104806400.

The previous prime is 643651660777. The next prime is 643651660823. The reversal of 643651660800 is 8066156346.

643651660800 is a `hidden beast` number, since 6 + 4 + 36 + 5 + 1 + 6 + 608 + 0 + 0 = 666.

It is an interprime number because it is at equal distance from previous prime (643651660777) and next prime (643651660823).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 179 ways as a sum of consecutive naturals, for example, 20762956785 + ... + 20762956815.

It is an arithmetic number, because the mean of its divisors is an integer number (1386281622).

Almost surely, 2^643651660800 is an apocalyptic number.

643651660800 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 643651660800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1372418805780).

643651660800 is an abundant number, since it is smaller than the sum of its proper divisors (2101185950760).

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

643651660800 is a wasteful number, since it uses less digits than its factorization.

643651660800 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 140 (or 77 counting only the distinct ones).

The product of its (nonzero) digits is 622080, while the sum is 45.

The spelling of 643651660800 in words is "six hundred forty-three billion, six hundred fifty-one million, six hundred sixty thousand, eight hundred".