643553556 has 12 divisors (see below), whose sum is σ = 1501624992. Its totient is φ = 214517848.

The previous prime is 643553551. The next prime is 643553569. The reversal of 643553556 is 655355346.

643553556 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a tau number, because it is divible by the number of its divisors (12).

It is a super-2 number, since 2×643553556² = 828322358880490272, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643553551) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 26814720 + ... + 26814743.

It is an arithmetic number, because the mean of its divisors is an integer number (125135416).

Almost surely, 2^643553556 is an apocalyptic number.

It is an amenable number.

643553556 is an abundant number, since it is smaller than the sum of its proper divisors (858071436).

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

643553556 is a wasteful number, since it uses less digits than its factorization.

643553556 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 53629470 (or 53629468 counting only the distinct ones).

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

The square root of 643553556 is about 25368.3573768583. The cubic root of 643553556 is about 863.3659131460.

The spelling of 643553556 in words is "six hundred forty-three million, five hundred fifty-three thousand, five hundred fifty-six".