8517720817 has 4 divisors (see below), whose sum is σ = 9018763236. Its totient is φ = 8016678400.

The previous prime is 8517720803. The next prime is 8517720821. The reversal of 8517720817 is 7180277158.

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 4789885681 + 3727835136 = 69209^2 + 61056^2 .

It is a cyclic number.

It is not a de Polignac number, because 8517720817 - 2⁷ = 8517720689 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (8517720017) 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, 250521184 + ... + 250521217.

It is an arithmetic number, because the mean of its divisors is an integer number (2254690809).

Almost surely, 2^8517720817 is an apocalyptic number.

It is an amenable number.

8517720817 is a deficient number, since it is larger than the sum of its proper divisors (501042419).

8517720817 is a wasteful number, since it uses less digits than its factorization.

8517720817 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 501042418.

The product of its (nonzero) digits is 219520, while the sum is 46.

The square root of 8517720817 is about 92291.4991589150. The cubic root of 8517720817 is about 2042.2448069684.

The spelling of 8517720817 in words is "eight billion, five hundred seventeen million, seven hundred twenty thousand, eight hundred seventeen".