643218 has 32 divisors (see below), whose sum is σ = 1382400. Its totient is φ = 199056.

The previous prime is 643217. The next prime is 643231. The reversal of 643218 is 812346.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (643213) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8103 + ... + 8181.

It is an arithmetic number, because the mean of its divisors is an integer number (43200).

2⁶⁴³²¹⁸ is an apocalyptic number.

643218 is an abundant number, since it is smaller than the sum of its proper divisors (739182).

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

643218 is a wasteful number, since it uses less digits than its factorization.

643218 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 166.

The product of its digits is 1152, while the sum is 24.

The square root of 643218 is about 802.0087281321. The cubic root of 643218 is about 86.3215830853.

It can be divided in two parts, 643 and 218, that added together give a triangular number (861 = T₄₁).

The spelling of 643218 in words is "six hundred forty-three thousand, two hundred eighteen".