643678 has 16 divisors (see below), whose sum is σ = 1152000. Its totient is φ = 263736.

The previous prime is 643661. The next prime is 643681. The reversal of 643678 is 876346.

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 643678.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 678 + ... + 1321.

It is an arithmetic number, because the mean of its divisors is an integer number (72000).

2⁶⁴³⁶⁷⁸ is an apocalyptic number.

643678 is a deficient number, since it is larger than the sum of its proper divisors (508322).

643678 is a wasteful number, since it uses less digits than its factorization.

643678 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2031.

The product of its digits is 24192, while the sum is 34.

The square root of 643678 is about 802.2954567988. The cubic root of 643678 is about 86.3421559270.

The spelling of 643678 in words is "six hundred forty-three thousand, six hundred seventy-eight".