11556372221 has 4 divisors (see below), whose sum is σ = 11593293852. Its totient is φ = 11519450592.

The previous prime is 11556372211. The next prime is 11556372263. The reversal of 11556372221 is 12227365511.

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 1445064196 + 10111308025 = 38014^2 + 100555^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-11556372221 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 (11556372211) 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 3 ways as a sum of consecutive naturals, for example, 18460346 + ... + 18460971.

It is an arithmetic number, because the mean of its divisors is an integer number (2898323463).

Almost surely, 2^11556372221 is an apocalyptic number.

It is an amenable number.

11556372221 is a deficient number, since it is larger than the sum of its proper divisors (36921631).

11556372221 is an equidigital number, since it uses as much as digits as its factorization.

11556372221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 36921630.

The product of its digits is 25200, while the sum is 35.

The spelling of 11556372221 in words is "eleven billion, five hundred fifty-six million, three hundred seventy-two thousand, two hundred twenty-one".