817788409 has 3 divisors (see below), whose sum is σ = 817817007. Its totient is φ = 817759812.

The previous prime is 817788407. The next prime is 817788421. The reversal of 817788409 is 904887718.

The square root of 817788409 is 28597.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in only one way, i.e., 813675625 + 4112784 = 28525^2 + 2028^2 .

It is not a de Polignac number, because 817788409 - 2¹ = 817788407 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (817788403) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 14299 + ... + 42895.

It is an arithmetic number, because the mean of its divisors is an integer number (272605669).

Almost surely, 2^817788409 is an apocalyptic number.

817788409 is the 28597-th square number.

817788409 is the 14299-th centered octagonal number.

It is an amenable number.

817788409 is a deficient number, since it is larger than the sum of its proper divisors (28598).

817788409 is an frugal number, since it uses more digits than its factorization.

817788409 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 57194 (or 28597 counting only the distinct ones).

The product of its (nonzero) digits is 903168, while the sum is 52.

The cubic root of 817788409 is about 935.1479301149.

The spelling of 817788409 in words is "eight hundred seventeen million, seven hundred eighty-eight thousand, four hundred nine".