643860720 has 240 divisors, whose sum is σ = 2347162272. Its totient is φ = 157532160.

The previous prime is 643860713. The next prime is 643860743. The reversal of 643860720 is 27068346.

643860720 is a `hidden beast` number, since 6 + 43 + 8 + 607 + 2 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (240).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 501199 + ... + 502481.

Almost surely, 2^643860720 is an apocalyptic number.

643860720 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 643860720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1173581136).

643860720 is an abundant number, since it is smaller than the sum of its proper divisors (1703301552).

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

643860720 is a wasteful number, since it uses less digits than its factorization.

643860720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1360 (or 1351 counting only the distinct ones).

The product of its (nonzero) digits is 48384, while the sum is 36.

The square root of 643860720 is about 25374.4107320742. The cubic root of 643860720 is about 863.5032509760.

The spelling of 643860720 in words is "six hundred forty-three million, eight hundred sixty thousand, seven hundred twenty".