643222656 has 96 divisors (see below), whose sum is σ = 1948424400. Its totient is φ = 203116032.

The previous prime is 643222651. The next prime is 643222667. The reversal of 643222656 is 656222346.

643222656 is a `hidden beast` number, since 643 + 2 + 2 + 2 + 6 + 5 + 6 = 666.

It is a tau number, because it is divible by the number of its divisors (96).

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 643222656.

It is not an unprimeable number, because it can be changed into a prime (643222651) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 7195 + ... + 36581.

Almost surely, 2^643222656 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 643222656, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (974212200).

643222656 is an abundant number, since it is smaller than the sum of its proper divisors (1305201744).

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

643222656 is a wasteful number, since it uses less digits than its factorization.

643222656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29426 (or 29411 counting only the distinct ones).

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

The square root of 643222656 is about 25361.8346339534. The cubic root of 643222656 is about 863.2179136741.

The spelling of 643222656 in words is "six hundred forty-three million, two hundred twenty-two thousand, six hundred fifty-six".