817286513521 has 9 divisors (see below), whose sum is σ = 862583673483. Its totient is φ = 774255161160.

The previous prime is 817286513513. The next prime is 817286513569. The reversal of 817286513521 is 125315682718.

The square root of 817286513521 is 904039.

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

It can be written as a sum of positive squares in only one way, i.e., 595615041121 + 221671472400 = 771761^2 + 470820^2 .

It is not a de Polignac number, because 817286513521 - 2³ = 817286513513 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (817286516521) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 17152951 + ... + 17200531.

It is an arithmetic number, because the mean of its divisors is an integer number (95842630387).

Almost surely, 2^817286513521 is an apocalyptic number.

817286513521 is the 904039-th square number.

817286513521 is the 452020-th centered octagonal number.

It is an amenable number.

817286513521 is a deficient number, since it is larger than the sum of its proper divisors (45297159962).

817286513521 is an frugal number, since it uses more digits than its factorization.

817286513521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 95200 (or 47600 counting only the distinct ones).

The product of its digits is 806400, while the sum is 49.

Multiplying 817286513521 by its sum of digits (49), we get a square (40047039162529 = 6328273²).

The spelling of 817286513521 in words is "eight hundred seventeen billion, two hundred eighty-six million, five hundred thirteen thousand, five hundred twenty-one".