840989 has 2 divisors, whose sum is σ = 840990. Its totient is φ = 840988.

The previous prime is 840979. The next prime is 840991. The reversal of 840989 is 989048.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 840889 + 100 = 917^2 + 10^2 .

It is a cyclic number.

It is not a de Polignac number, because 840989 - 2⁸ = 840733 is a prime.

Together with 840991, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (840929) 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, 420494 + 420495.

It is an arithmetic number, because the mean of its divisors is an integer number (420495).

2⁸⁴⁰⁹⁸⁹ is an apocalyptic number.

It is an amenable number.

840989 is a deficient number, since it is larger than the sum of its proper divisors (1).

840989 is an equidigital number, since it uses as much as digits as its factorization.

840989 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 20736, while the sum is 38.

The square root of 840989 is about 917.0545240061. The cubic root of 840989 is about 94.3908952365.

The spelling of 840989 in words is "eight hundred forty thousand, nine hundred eighty-nine".