643888 has 20 divisors (see below), whose sum is σ = 1426000. Its totient is φ = 275904.

The previous prime is 643883. The next prime is 643889. The reversal of 643888 is 888346.

It is not an unprimeable number, because it can be changed into a prime (643883) 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, 2763 + ... + 2986.

It is an arithmetic number, because the mean of its divisors is an integer number (71300).

2⁶⁴³⁸⁸⁸ is an apocalyptic number.

It is an amenable number.

643888 is an abundant number, since it is smaller than the sum of its proper divisors (782112).

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

643888 is a wasteful number, since it uses less digits than its factorization.

643888 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5764 (or 5758 counting only the distinct ones).

The product of its digits is 36864, while the sum is 37.

The square root of 643888 is about 802.4263206052. The cubic root of 643888 is about 86.3515446179.

It can be divided in two parts, 64 and 3888, that multiplied together give a 5-th power (248832 = 12⁵).

The spelling of 643888 in words is "six hundred forty-three thousand, eight hundred eighty-eight".