2561188121 has 2 divisors, whose sum is σ = 2561188122. Its totient is φ = 2561188120.

The previous prime is 2561188117. The next prime is 2561188129. The reversal of 2561188121 is 1218811652.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 2171560000 + 389628121 = 46600^2 + 19739^2 .

It is a cyclic number.

It is not a de Polignac number, because 2561188121 - 2² = 2561188117 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (2561188129) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1280594060 + 1280594061.

It is an arithmetic number, because the mean of its divisors is an integer number (1280594061).

Almost surely, 2^2561188121 is an apocalyptic number.

It is an amenable number.

2561188121 is a deficient number, since it is larger than the sum of its proper divisors (1).

2561188121 is an equidigital number, since it uses as much as digits as its factorization.

2561188121 is an evil number, because the sum of its binary digits is even.

The product of its digits is 7680, while the sum is 35.

The square root of 2561188121 is about 50608.1823522639. The cubic root of 2561188121 is about 1368.1923556860.

Adding to 2561188121 its reverse (1218811652), we get a palindrome (3779999773).

The spelling of 2561188121 in words is "two billion, five hundred sixty-one million, one hundred eighty-eight thousand, one hundred twenty-one".