816909 has 8 divisors (see below), whose sum is σ = 1093920. Its totient is φ = 542256.

The previous prime is 816899. The next prime is 816911. The reversal of 816909 is 909618.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 816909 - 2⁸ = 816653 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a self number, because there is not a number n which added to its sum of digits gives 816909.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (816919) 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 in 7 ways as a sum of consecutive naturals, for example, 522 + ... + 1380.

It is an arithmetic number, because the mean of its divisors is an integer number (136740).

2⁸¹⁶⁹⁰⁹ is an apocalyptic number.

It is an amenable number.

816909 is a deficient number, since it is larger than the sum of its proper divisors (277011).

816909 is a wasteful number, since it uses less digits than its factorization.

816909 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1179.

The product of its (nonzero) digits is 3888, while the sum is 33.

The square root of 816909 is about 903.8301831650. The cubic root of 816909 is about 93.4812606024.

The spelling of 816909 in words is "eight hundred sixteen thousand, nine hundred nine".