643475556 has 96 divisors (see below), whose sum is σ = 1746984960. Its totient is φ = 204573600.

The previous prime is 643475533. The next prime is 643475563. The reversal of 643475556 is 655574346.

643475556 is a `hidden beast` number, since 64 + 34 + 7 + 5 + 556 = 666.

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 31 ways as a sum of consecutive naturals, for example, 236355 + ... + 239061.

It is an arithmetic number, because the mean of its divisors is an integer number (18197760).

Almost surely, 2^643475556 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 643475556, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (873492480).

643475556 is an abundant number, since it is smaller than the sum of its proper divisors (1103509404).

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

643475556 is a wasteful number, since it uses less digits than its factorization.

643475556 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2822 (or 2814 counting only the distinct ones).

The product of its digits is 1512000, while the sum is 45.

The square root of 643475556 is about 25366.8199820159. The cubic root of 643475556 is about 863.3310311684.

The spelling of 643475556 in words is "six hundred forty-three million, four hundred seventy-five thousand, five hundred fifty-six".