840078089 has 2 divisors, whose sum is σ = 840078090. Its totient is φ = 840078088.

The previous prime is 840078067. The next prime is 840078091. The reversal of 840078089 is 980870048.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 520204864 + 319873225 = 22808^2 + 17885^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-840078089 is a prime.

Together with 840078091, it forms a pair of twin primes.

It is a Chen prime.

It is equal to p_43099199 and since 840078089 and 43099199 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (840078689) 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, 420039044 + 420039045.

It is an arithmetic number, because the mean of its divisors is an integer number (420039045).

Almost surely, 2^840078089 is an apocalyptic number.

It is an amenable number.

840078089 is a deficient number, since it is larger than the sum of its proper divisors (1).

840078089 is an equidigital number, since it uses as much as digits as its factorization.

840078089 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 129024, while the sum is 44.

The square root of 840078089 is about 28984.1006243078. The cubic root of 840078089 is about 943.5680332530.

The spelling of 840078089 in words is "eight hundred forty million, seventy-eight thousand, eighty-nine".