15605606221 has 4 divisors (see below), whose sum is σ = 15614331100. Its totient is φ = 15596881344.

The previous prime is 15605606189. The next prime is 15605606249. The reversal of 15605606221 is 12260650651.

15605606221 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, and also an emirpimes, since its reverse is a distinct semiprime: 12260650651 = 9029 ⋅1357919.

It can be written as a sum of positive squares in 2 ways, for example, as 11446646121 + 4158960100 = 106989^2 + 64490^2 .

It is a cyclic number.

It is not a de Polignac number, because 15605606221 - 2⁵ = 15605606189 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 (15605606321) 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, 4359756 + ... + 4363333.

It is an arithmetic number, because the mean of its divisors is an integer number (3903582775).

Almost surely, 2^15605606221 is an apocalyptic number.

It is an amenable number.

15605606221 is a deficient number, since it is larger than the sum of its proper divisors (8724879).

15605606221 is an equidigital number, since it uses as much as digits as its factorization.

15605606221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8724878.

The product of its (nonzero) digits is 21600, while the sum is 34.

The spelling of 15605606221 in words is "fifteen billion, six hundred five million, six hundred six thousand, two hundred twenty-one".