819391 has 2 divisors, whose sum is σ = 819392. Its totient is φ = 819390.

The previous prime is 819389. The next prime is 819407. The reversal of 819391 is 193918.

819391 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 819391 - 2¹ = 819389 is a prime.

It is a super-2 number, since 2×819391² = 1342803221762, which contains 22 as substring.

Together with 819389, 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 (819311) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 409695 + 409696.

It is an arithmetic number, because the mean of its divisors is an integer number (409696).

2⁸¹⁹³⁹¹ is an apocalyptic number.

819391 is the 573-rd centered pentagonal number.

819391 is a deficient number, since it is larger than the sum of its proper divisors (1).

819391 is an equidigital number, since it uses as much as digits as its factorization.

819391 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1944, while the sum is 31.

The square root of 819391 is about 905.2021873593. The cubic root of 819391 is about 93.5758390289.

The spelling of 819391 in words is "eight hundred nineteen thousand, three hundred ninety-one".