261310121 has 2 divisors, whose sum is σ = 261310122. Its totient is φ = 261310120.

The previous prime is 261310109. The next prime is 261310139. The reversal of 261310121 is 121013162.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 258052096 + 3258025 = 16064^2 + 1805^2 .

It is a cyclic number.

It is not a de Polignac number, because 261310121 - 2⁶ = 261310057 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 261310121.

It is not a weakly prime, because it can be changed into another prime (261310171) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130655060 + 130655061.

It is an arithmetic number, because the mean of its divisors is an integer number (130655061).

Almost surely, 2^261310121 is an apocalyptic number.

It is an amenable number.

261310121 is a deficient number, since it is larger than the sum of its proper divisors (1).

261310121 is an equidigital number, since it uses as much as digits as its factorization.

261310121 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 72, while the sum is 17.

The square root of 261310121 is about 16165.0895759968. The cubic root of 261310121 is about 639.3206667037.

Adding to 261310121 its reverse (121013162), we get a palindrome (382323283).

The spelling of 261310121 in words is "two hundred sixty-one million, three hundred ten thousand, one hundred twenty-one".