643278 has 16 divisors (see below), whose sum is σ = 1331280. Its totient is φ = 206976.

The previous prime is 643273. The next prime is 643301. The reversal of 643278 is 872346.

643278 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a d-powerful number, because it can be written as 6² + 4³ + 2¹⁹ + 3⁶ + 7⁶ + 8³ .

It is a Curzon number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 643278.

It is not an unprimeable number, because it can be changed into a prime (643273) by changing a digit.

643278 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1675 + ... + 2022.

It is an arithmetic number, because the mean of its divisors is an integer number (83205).

2⁶⁴³²⁷⁸ is an apocalyptic number.

643278 is an abundant number, since it is smaller than the sum of its proper divisors (688002).

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

643278 is a wasteful number, since it uses less digits than its factorization.

643278 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3731.

The product of its digits is 8064, while the sum is 30.

The square root of 643278 is about 802.0461333365. The cubic root of 643278 is about 86.3242670556.

The spelling of 643278 in words is "six hundred forty-three thousand, two hundred seventy-eight".