643355556 has 48 divisors (see below), whose sum is σ = 1555499904. Its totient is φ = 206793216.

The previous prime is 643355549. The next prime is 643355567. The reversal of 643355556 is 655553346.

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, 43761 + ... + 56583.

It is an arithmetic number, because the mean of its divisors is an integer number (32406248).

Almost surely, 2^643355556 is an apocalyptic number.

It is an amenable number.

643355556 is an abundant number, since it is smaller than the sum of its proper divisors (912144348).

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

643355556 is a wasteful number, since it uses less digits than its factorization.

643355556 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12980 (or 12978 counting only the distinct ones).

The product of its digits is 810000, while the sum is 42.

The square root of 643355556 is about 25364.4545772228. The cubic root of 643355556 is about 863.2773610829.

The spelling of 643355556 in words is "six hundred forty-three million, three hundred fifty-five thousand, five hundred fifty-six".