684643 has 2 divisors, whose sum is σ = 684644. Its totient is φ = 684642.

The previous prime is 684637. The next prime is 684647. The reversal of 684643 is 346486.

684643 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-684643 is a prime.

684643 is a lucky number.

It is not a weakly prime, because it can be changed into another prime (684647) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 342321 + 342322.

It is an arithmetic number, because the mean of its divisors is an integer number (342322).

2⁶⁸⁴⁶⁴³ is an apocalyptic number.

684643 is a deficient number, since it is larger than the sum of its proper divisors (1).

684643 is an equidigital number, since it uses as much as digits as its factorization.

684643 is an evil number, because the sum of its binary digits is even.

The product of its digits is 13824, while the sum is 31.

The square root of 684643 is about 827.4315681674. The cubic root of 684643 is about 88.1362816065.

It can be divided in two parts, 6846 and 43, that added together give a square (6889 = 83²).

The spelling of 684643 in words is "six hundred eighty-four thousand, six hundred forty-three".