840643 has 2 divisors, whose sum is σ = 840644. Its totient is φ = 840642.

The previous prime is 840611. The next prime is 840661. The reversal of 840643 is 346048.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 840643 - 2⁵ = 840611 is a prime.

It is not a weakly prime, because it can be changed into another prime (840683) by changing a digit.

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 as a sum of consecutive naturals, namely, 420321 + 420322.

It is an arithmetic number, because the mean of its divisors is an integer number (420322).

2⁸⁴⁰⁶⁴³ is an apocalyptic number.

840643 is a deficient number, since it is larger than the sum of its proper divisors (1).

840643 is an equidigital number, since it uses as much as digits as its factorization.

840643 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2304, while the sum is 25.

The square root of 840643 is about 916.8658571460. The cubic root of 840643 is about 94.3779486820.

The spelling of 840643 in words is "eight hundred forty thousand, six hundred forty-three".