11515612221 has 12 divisors (see below), whose sum is σ = 16637268960. Its totient is φ = 7675410120.

The previous prime is 11515612187. The next prime is 11515612223. The reversal of 11515612221 is 12221651511.

It is a happy number.

11515612221 is a `hidden beast` number, since 1 + 1 + 515 + 6 + 122 + 21 = 666.

11515612221 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 11515612221 - 2¹¹ = 11515610173 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (11515612223) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 94161 + ... + 178598.

It is an arithmetic number, because the mean of its divisors is an integer number (1386439080).

Almost surely, 2^11515612221 is an apocalyptic number.

It is an amenable number.

11515612221 is a deficient number, since it is larger than the sum of its proper divisors (5121656739).

11515612221 is a wasteful number, since it uses less digits than its factorization.

11515612221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 277456 (or 277453 counting only the distinct ones).

The product of its digits is 1200, while the sum is 27.

The spelling of 11515612221 in words is "eleven billion, five hundred fifteen million, six hundred twelve thousand, two hundred twenty-one".