643460256 has 144 divisors (see below), whose sum is σ = 1888862976. Its totient is φ = 207664128.

The previous prime is 643460171. The next prime is 643460297. The reversal of 643460256 is 652064346.

643460256 is a `hidden beast` number, since 6 + 43 + 4 + 602 + 5 + 6 = 666.

It is a tau number, because it is divible by the number of its divisors (144).

It is a super-2 number, since 2×643460256² = 828082202103171072, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a self number, because there is not a number n which added to its sum of digits gives 643460256.

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 23 ways as a sum of consecutive naturals, for example, 2761516 + ... + 2761748.

It is an arithmetic number, because the mean of its divisors is an integer number (13117104).

Almost surely, 2^643460256 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 643460256, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (944431488).

643460256 is an abundant number, since it is smaller than the sum of its proper divisors (1245402720).

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

643460256 is a wasteful number, since it uses less digits than its factorization.

643460256 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 515 (or 504 counting only the distinct ones).

The product of its (nonzero) digits is 103680, while the sum is 36.

The square root of 643460256 is about 25366.5184051734. The cubic root of 643460256 is about 863.3241886037.

The spelling of 643460256 in words is "six hundred forty-three million, four hundred sixty thousand, two hundred fifty-six".