2556221161 has 6 divisors (see below), whose sum is σ = 2767979310. Its totient is φ = 2359588608.

The previous prime is 2556221149. The next prime is 2556221177. The reversal of 2556221161 is 1611226552.

It can be written as a sum of positive squares in 3 ways, for example, as 334890000 + 2221331161 = 18300^2 + 47131^2 .

It is a de Polignac number, because none of the positive numbers 2^k-2556221161 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2556221131) 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 5 ways as a sum of consecutive naturals, for example, 7562616 + ... + 7562953.

It is an arithmetic number, because the mean of its divisors is an integer number (461329885).

Almost surely, 2^2556221161 is an apocalyptic number.

It is an amenable number.

2556221161 is a deficient number, since it is larger than the sum of its proper divisors (211758149).

2556221161 is a wasteful number, since it uses less digits than its factorization.

2556221161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15125595 (or 15125582 counting only the distinct ones).

The product of its digits is 7200, while the sum is 31.

The square root of 2556221161 is about 50559.0858402325. The cubic root of 2556221161 is about 1367.3073296529.

The spelling of 2556221161 in words is "two billion, five hundred fifty-six million, two hundred twenty-one thousand, one hundred sixty-one".