643580640 has 144 divisors (see below), whose sum is σ = 2277697968. Its totient is φ = 171611136.

The previous prime is 643580621. The next prime is 643580647. The reversal of 643580640 is 46085346.

643580640 is a `hidden beast` number, since 6 + 4 + 3 + 5 + 8 + 0 + 640 = 666.

It is a tau number, because it is divible by the number of its divisors (144).

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

It is a junction number, because it is equal to n+sod(n) for n = 643580595 and 643580604.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643580647) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 30604 + ... + 47156.

It is an arithmetic number, because the mean of its divisors is an integer number (15817347).

Almost surely, 2^643580640 is an apocalyptic number.

643580640 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 643580640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1138848984).

643580640 is an abundant number, since it is smaller than the sum of its proper divisors (1634117328).

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

643580640 is a wasteful number, since it uses less digits than its factorization.

643580640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16583 (or 16563 counting only the distinct ones).

The product of its (nonzero) digits is 69120, while the sum is 36.

The square root of 643580640 is about 25368.8911858599. The cubic root of 643580640 is about 863.3780245826.

The spelling of 643580640 in words is "six hundred forty-three million, five hundred eighty thousand, six hundred forty".