643523320 has 64 divisors (see below), whose sum is σ = 1585720800. Its totient is φ = 233095680.

The previous prime is 643523303. The next prime is 643523323. The reversal of 643523320 is 23325346.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643523323) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 115642 + ... + 121078.

Almost surely, 2^643523320 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 643523320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (792860400).

643523320 is an abundant number, since it is smaller than the sum of its proper divisors (942197480).

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

643523320 is a wasteful number, since it uses less digits than its factorization.

643523320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5728 (or 5724 counting only the distinct ones).

The product of its (nonzero) digits is 12960, while the sum is 28.

The square root of 643523320 is about 25367.7614306032. The cubic root of 643523320 is about 863.3523917950.

Adding to 643523320 its reverse (23325346), we get a palindrome (666848666).

The spelling of 643523320 in words is "six hundred forty-three million, five hundred twenty-three thousand, three hundred twenty".