11521660921 has 3 divisors (see below), whose sum is σ = 11521768261. Its totient is φ = 11521553582.

The previous prime is 11521660901. The next prime is 11521660939. The reversal of 11521660921 is 12906612511.

It is a happy number.

The square root of 11521660921 is 107339.

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 is not a de Polignac number, because 11521660921 - 2¹¹ = 11521658873 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (11521660901) 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 2 ways as a sum of consecutive naturals, for example, 53670 + ... + 161008.

Almost surely, 2^11521660921 is an apocalyptic number.

11521660921 is the 107339-th square number.

11521660921 is the 53670-th centered octagonal number.

It is an amenable number.

11521660921 is a deficient number, since it is larger than the sum of its proper divisors (107340).

11521660921 is an frugal number, since it uses more digits than its factorization.

11521660921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 214678 (or 107339 counting only the distinct ones).

The product of its (nonzero) digits is 6480, while the sum is 34.

The spelling of 11521660921 in words is "eleven billion, five hundred twenty-one million, six hundred sixty thousand, nine hundred twenty-one".