643445320 has 32 divisors (see below), whose sum is σ = 1654574400. Its totient is φ = 220609728.

The previous prime is 643445303. The next prime is 643445339. The reversal of 643445320 is 23544346.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1148730 + ... + 1149289.

It is an arithmetic number, because the mean of its divisors is an integer number (51705450).

Almost surely, 2^643445320 is an apocalyptic number.

It is an amenable number.

643445320 is an abundant number, since it is smaller than the sum of its proper divisors (1011129080).

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

643445320 is a wasteful number, since it uses less digits than its factorization.

643445320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2298037 (or 2298033 counting only the distinct ones).

The product of its (nonzero) digits is 34560, while the sum is 31.

The square root of 643445320 is about 25366.2239996417. The cubic root of 643445320 is about 863.3175087247.

Adding to 643445320 its reverse (23544346), we get a palindrome (666989666).

The spelling of 643445320 in words is "six hundred forty-three million, four hundred forty-five thousand, three hundred twenty".