816688013 has 4 divisors (see below), whose sum is σ = 838760700. Its totient is φ = 794615328.

The previous prime is 816688009. The next prime is 816688021. The reversal of 816688013 is 310886618.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 780531844 + 36156169 = 27938^2 + 6013^2 .

It is a cyclic number.

It is not a de Polignac number, because 816688013 - 2² = 816688009 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (816688073) 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, 11036288 + ... + 11036361.

It is an arithmetic number, because the mean of its divisors is an integer number (209690175).

Almost surely, 2^816688013 is an apocalyptic number.

It is an amenable number.

816688013 is a deficient number, since it is larger than the sum of its proper divisors (22072687).

816688013 is a wasteful number, since it uses less digits than its factorization.

816688013 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22072686.

The product of its (nonzero) digits is 55296, while the sum is 41.

The square root of 816688013 is about 28577.7538130624. The cubic root of 816688013 is about 934.7283044827.

The spelling of 816688013 in words is "eight hundred sixteen million, six hundred eighty-eight thousand, thirteen".