643520240 has 80 divisors (see below), whose sum is σ = 1667036160. Its totient is φ = 229013760.

The previous prime is 643520221. The next prime is 643520263. The reversal of 643520240 is 42025346.

It is a tau number, because it is divible by the number of its divisors (80).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 33581 + ... + 49139.

It is an arithmetic number, because the mean of its divisors is an integer number (20837952).

Almost surely, 2^643520240 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 643520240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (833518080).

643520240 is an abundant number, since it is smaller than the sum of its proper divisors (1023515920).

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

643520240 is a wasteful number, since it uses less digits than its factorization.

643520240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15630 (or 15624 counting only the distinct ones).

The product of its (nonzero) digits is 5760, while the sum is 26.

The square root of 643520240 is about 25367.7007235579. The cubic root of 643520240 is about 863.3510144144.

Adding to 643520240 its reverse (42025346), we get a palindrome (685545586).

The spelling of 643520240 in words is "six hundred forty-three million, five hundred twenty thousand, two hundred forty".