11997293891521 has 9 divisors (see below), whose sum is σ = 12013550287011. Its totient is φ = 11981059478064.

The previous prime is 11997293891519. The next prime is 11997293891549. The reversal of 11997293891521 is 12519839279911.

The square root of 11997293891521 is 3463711.

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., 9941970241921 + 2055323649600 = 3153089^2 + 1433640^2 .

It is not a de Polignac number, because 11997293891521 - 2¹ = 11997293891519 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (11997293891591) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 3183148525 + ... + 3183152293.

It is an arithmetic number, because the mean of its divisors is an integer number (1334838920779).

Almost surely, 2^{11997293891521} is an apocalyptic number.

11997293891521 is the 3463711-st square number.

11997293891521 is the 1731856-th centered octagonal number.

It is an amenable number.

11997293891521 is a deficient number, since it is larger than the sum of its proper divisors (16256395490).

11997293891521 is an frugal number, since it uses more digits than its factorization.

11997293891521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9376 (or 4688 counting only the distinct ones).

The product of its digits is 22044960, while the sum is 67.

The spelling of 11997293891521 in words is "eleven trillion, nine hundred ninety-seven billion, two hundred ninety-three million, eight hundred ninety-one thousand, five hundred twenty-one".