11505251221 has 4 divisors (see below), whose sum is σ = 11530208844. Its totient is φ = 11480293600.

The previous prime is 11505251207. The next prime is 11505251237. The reversal of 11505251221 is 12215250511.

It is a happy number.

11505251221 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 6728920900 + 4776330321 = 82030^2 + 69111^2 .

It is a cyclic number.

It is not a de Polignac number, because 11505251221 - 2¹⁵ = 11505218453 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (11505251201) 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 3 ways as a sum of consecutive naturals, for example, 12478120 + ... + 12479041.

It is an arithmetic number, because the mean of its divisors is an integer number (2882552211).

Almost surely, 2^11505251221 is an apocalyptic number.

It is an amenable number.

11505251221 is a deficient number, since it is larger than the sum of its proper divisors (24957623).

11505251221 is an equidigital number, since it uses as much as digits as its factorization.

11505251221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24957622.

The product of its (nonzero) digits is 1000, while the sum is 25.

The spelling of 11505251221 in words is "eleven billion, five hundred five million, two hundred fifty-one thousand, two hundred twenty-one".