816609 has 4 divisors (see below), whose sum is σ = 1088816. Its totient is φ = 544404.

The previous prime is 816593. The next prime is 816649. The reversal of 816609 is 906618.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 816609 - 2⁴ = 816593 is a prime.

It is a D-number.

It is a Duffinian number.

816609 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (816649) 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 3 ways as a sum of consecutive naturals, for example, 136099 + ... + 136104.

It is an arithmetic number, because the mean of its divisors is an integer number (272204).

2⁸¹⁶⁶⁰⁹ is an apocalyptic number.

It is an amenable number.

816609 is a deficient number, since it is larger than the sum of its proper divisors (272207).

816609 is a wasteful number, since it uses less digits than its factorization.

816609 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 272206.

The product of its (nonzero) digits is 2592, while the sum is 30.

The square root of 816609 is about 903.6642075461. The cubic root of 816609 is about 93.4698159120.

Subtracting 816609 from its reverse (906618), we obtain a palindrome (90009).

The spelling of 816609 in words is "eight hundred sixteen thousand, six hundred nine".