816528213857 has 4 divisors (see below), whose sum is σ = 825702688260. Its totient is φ = 807353739456.

The previous prime is 816528213841. The next prime is 816528213859. The reversal of 816528213857 is 758312825618.

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 95453809936 + 721074403921 = 308956^2 + 849161^2 .

It is a cyclic number.

It is not a de Polignac number, because 816528213857 - 2⁴ = 816528213841 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (816528213859) 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, 4587237068 + ... + 4587237245.

It is an arithmetic number, because the mean of its divisors is an integer number (206425672065).

Almost surely, 2^816528213857 is an apocalyptic number.

It is an amenable number.

816528213857 is a deficient number, since it is larger than the sum of its proper divisors (9174474403).

816528213857 is an equidigital number, since it uses as much as digits as its factorization.

816528213857 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9174474402.

The product of its digits is 6451200, while the sum is 56.

The spelling of 816528213857 in words is "eight hundred sixteen billion, five hundred twenty-eight million, two hundred thirteen thousand, eight hundred fifty-seven".