816563309 has 4 divisors (see below), whose sum is σ = 817127520. Its totient is φ = 815999100.

The previous prime is 816563269. The next prime is 816563311. The reversal of 816563309 is 903365618.

816563309 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 a cyclic number.

It is not a de Polignac number, because 816563309 - 2⁸ = 816563053 is a prime.

It is a super-3 number, since 3×816563309³ (a number of 28 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (816563369) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 279929 + ... + 282830.

It is an arithmetic number, because the mean of its divisors is an integer number (204281880).

Almost surely, 2^816563309 is an apocalyptic number.

It is an amenable number.

816563309 is a deficient number, since it is larger than the sum of its proper divisors (564211).

816563309 is a wasteful number, since it uses less digits than its factorization.

816563309 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 564210.

The product of its (nonzero) digits is 116640, while the sum is 41.

The square root of 816563309 is about 28575.5718927898. The cubic root of 816563309 is about 934.6807260154.

The spelling of 816563309 in words is "eight hundred sixteen million, five hundred sixty-three thousand, three hundred nine".