78815990569 has 4 divisors (see below), whose sum is σ = 78821760196. Its totient is φ = 78810220944.

The previous prime is 78815990521. The next prime is 78815990581. The reversal of 78815990569 is 96509951887.

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 46976227600 + 31839762969 = 216740^2 + 178437^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-78815990569 is a prime.

It is a super-2 number, since 2×78815990569² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78815990509) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2864274 + ... + 2891659.

It is an arithmetic number, because the mean of its divisors is an integer number (19705440049).

Almost surely, 2^78815990569 is an apocalyptic number.

It is an amenable number.

78815990569 is a deficient number, since it is larger than the sum of its proper divisors (5769627).

78815990569 is a wasteful number, since it uses less digits than its factorization.

78815990569 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5769626.

The product of its (nonzero) digits is 48988800, while the sum is 67.

The spelling of 78815990569 in words is "seventy-eight billion, eight hundred fifteen million, nine hundred ninety thousand, five hundred sixty-nine".