643556 has 12 divisors (see below), whose sum is σ = 1131900. Its totient is φ = 320160.

The previous prime is 643553. The next prime is 643567. The reversal of 643556 is 655346.

643556 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 341056 + 302500 = 584^2 + 550^2 .

It is a hoax number, since the sum of its digits (29) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (643553) 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, 1166 + ... + 1626.

It is an arithmetic number, because the mean of its divisors is an integer number (94325).

2⁶⁴³⁵⁵⁶ is an apocalyptic number.

It is an amenable number.

643556 is a deficient number, since it is larger than the sum of its proper divisors (488344).

643556 is a wasteful number, since it uses less digits than its factorization.

643556 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 814 (or 812 counting only the distinct ones).

The product of its digits is 10800, while the sum is 29.

The square root of 643556 is about 802.2194213555. The cubic root of 643556 is about 86.3367006069.

The spelling of 643556 in words is "six hundred forty-three thousand, five hundred fifty-six".