816608721 has 8 divisors (see below), whose sum is σ = 1136151360. Its totient is φ = 520735952.

The previous prime is 816608717. The next prime is 816608827. The reversal of 816608721 is 127806618.

816608721 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It is a cyclic number.

It is not a de Polignac number, because 816608721 - 2² = 816608717 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 816608721.

It is not an unprimeable number, because it can be changed into a prime (816608711) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5917386 + ... + 5917523.

It is an arithmetic number, because the mean of its divisors is an integer number (142018920).

Almost surely, 2^816608721 is an apocalyptic number.

It is an amenable number.

816608721 is a deficient number, since it is larger than the sum of its proper divisors (319542639).

816608721 is a wasteful number, since it uses less digits than its factorization.

816608721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11834935.

The product of its (nonzero) digits is 32256, while the sum is 39.

The square root of 816608721 is about 28576.3664765134. The cubic root of 816608721 is about 934.6980526712.

The spelling of 816608721 in words is "eight hundred sixteen million, six hundred eight thousand, seven hundred twenty-one".