819409 has 2 divisors, whose sum is σ = 819410. Its totient is φ = 819408.

The previous prime is 819407. The next prime is 819419. The reversal of 819409 is 904918.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 810000 + 9409 = 900^2 + 97^2 .

It is a cyclic number.

It is not a de Polignac number, because 819409 - 2¹ = 819407 is a prime.

It is a super-2 number, since 2×819409² = 1342862218562, which contains 22 as substring.

Together with 819407, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (819407) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 409704 + 409705.

It is an arithmetic number, because the mean of its divisors is an integer number (409705).

2⁸¹⁹⁴⁰⁹ is an apocalyptic number.

It is an amenable number.

819409 is a deficient number, since it is larger than the sum of its proper divisors (1).

819409 is an equidigital number, since it uses as much as digits as its factorization.

819409 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2592, while the sum is 31.

The square root of 819409 is about 905.2121298348. The cubic root of 819409 is about 93.5765242341.

It can be divided in two parts, 819 and 409, that multiplied together give a triangular number (334971 = T₈₁₈).

The spelling of 819409 in words is "eight hundred nineteen thousand, four hundred nine".