643504820 has 72 divisors (see below), whose sum is σ = 1596172032. Its totient is φ = 213468480.

The previous prime is 643504819. The next prime is 643504831. The reversal of 643504820 is 28405346.

643504820 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 132149 + ... + 136931.

It is an arithmetic number, because the mean of its divisors is an integer number (22169056).

Almost surely, 2^643504820 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 643504820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (798086016).

643504820 is an abundant number, since it is smaller than the sum of its proper divisors (952667212).

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

643504820 is a wasteful number, since it uses less digits than its factorization.

643504820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4861 (or 4828 counting only the distinct ones).

The product of its (nonzero) digits is 23040, while the sum is 32.

The square root of 643504820 is about 25367.3967919454. The cubic root of 643504820 is about 863.3441185013.

The spelling of 643504820 in words is "six hundred forty-three million, five hundred four thousand, eight hundred twenty".