643440260 has 24 divisors (see below), whose sum is σ = 1355500440. Its totient is φ = 256561664.

The previous prime is 643440251. The next prime is 643440271. The reversal of 643440260 is 62044346.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 14032516 + 629407744 = 3746^2 + 25088^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 44405 + ... + 57084.

It is an arithmetic number, because the mean of its divisors is an integer number (56479185).

Almost surely, 2^643440260 is an apocalyptic number.

It is an amenable number.

643440260 is an abundant number, since it is smaller than the sum of its proper divisors (712060180).

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

643440260 is a wasteful number, since it uses less digits than its factorization.

643440260 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 101815 (or 101813 counting only the distinct ones).

The product of its (nonzero) digits is 13824, while the sum is 29.

The square root of 643440260 is about 25366.1242605172. The cubic root of 643440260 is about 863.3152457000.

The spelling of 643440260 in words is "six hundred forty-three million, four hundred forty thousand, two hundred sixty".