811871279521 has 9 divisors (see below), whose sum is σ = 823211848179. Its totient is φ = 800684880336.

The previous prime is 811871279467. The next prime is 811871279561. The reversal of 811871279521 is 125972178118.

The square root of 811871279521 is 901039.

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., 460857688225 + 351013591296 = 678865^2 + 592464^2 .

It is not a de Polignac number, because 811871279521 - 2³¹ = 809723795873 is a prime.

It is a super-2 number, since 2×811871279521² (a number of 25 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (811871279561) 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 8 ways as a sum of consecutive naturals, for example, 65769676 + ... + 65782018.

It is an arithmetic number, because the mean of its divisors is an integer number (91467983131).

Almost surely, 2^811871279521 is an apocalyptic number.

811871279521 is the 901039-th square number.

811871279521 is the 450520-th centered octagonal number.

It is an amenable number.

811871279521 is a deficient number, since it is larger than the sum of its proper divisors (11340568658).

811871279521 is an frugal number, since it uses more digits than its factorization.

811871279521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24832 (or 12416 counting only the distinct ones).

The product of its digits is 564480, while the sum is 52.

The spelling of 811871279521 in words is "eight hundred eleven billion, eight hundred seventy-one million, two hundred seventy-nine thousand, five hundred twenty-one".