643521330 has 96 divisors (see below), whose sum is σ = 1711015488. Its totient is φ = 167760000.

The previous prime is 643521323. The next prime is 643521331. The reversal of 643521330 is 33125346.

It is a happy number.

643521330 is a `hidden beast` number, since 643 + 5 + 2 + 13 + 3 + 0 = 666.

643521330 is digitally balanced in base 6, because in such base it contains all the possibile digits an equal number of times.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 643521294 and 643521303.

It is not an unprimeable number, because it can be changed into a prime (643521331) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1377757 + ... + 1378223.

It is an arithmetic number, because the mean of its divisors is an integer number (17823078).

Almost surely, 2^643521330 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 643521330, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (855507744).

643521330 is an abundant number, since it is smaller than the sum of its proper divisors (1067494158).

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

643521330 is a wasteful number, since it uses less digits than its factorization.

643521330 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 792 (or 789 counting only the distinct ones).

The product of its (nonzero) digits is 6480, while the sum is 27.

The square root of 643521330 is about 25367.7222075613. The cubic root of 643521330 is about 863.3515018645.

Adding to 643521330 its reverse (33125346), we get a palindrome (676646676).

The spelling of 643521330 in words is "six hundred forty-three million, five hundred twenty-one thousand, three hundred thirty".