643928225256 has 384 divisors, whose sum is σ = 1923257520000. Its totient is φ = 202055285376.

The previous prime is 643928225231. The next prime is 643928225261. The reversal of 643928225256 is 652522829346.

643928225256 is a `hidden beast` number, since 6 + 4 + 3 + 92 + 8 + 22 + 525 + 6 = 666.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 1699018875 + ... + 1699019253.

It is an arithmetic number, because the mean of its divisors is an integer number (5008483125).

Almost surely, 2^643928225256 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 643928225256, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (961628760000).

643928225256 is an abundant number, since it is smaller than the sum of its proper divisors (1279329294744).

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

643928225256 is a wasteful number, since it uses less digits than its factorization.

643928225256 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 713 (or 672 counting only the distinct ones).

The product of its digits is 12441600, while the sum is 54.

The spelling of 643928225256 in words is "six hundred forty-three billion, nine hundred twenty-eight million, two hundred twenty-five thousand, two hundred fifty-six".