261904961 has 2 divisors, whose sum is σ = 261904962. Its totient is φ = 261904960.

The previous prime is 261904939. The next prime is 261904997. The reversal of 261904961 is 169409162.

261904961 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 195580225 + 66324736 = 13985^2 + 8144^2 .

It is a cyclic number.

It is not a de Polignac number, because 261904961 - 2¹⁰ = 261903937 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (261904901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130952480 + 130952481.

It is an arithmetic number, because the mean of its divisors is an integer number (130952481).

Almost surely, 2^261904961 is an apocalyptic number.

It is an amenable number.

261904961 is a deficient number, since it is larger than the sum of its proper divisors (1).

261904961 is an equidigital number, since it uses as much as digits as its factorization.

261904961 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 23328, while the sum is 38.

The square root of 261904961 is about 16183.4780254431. The cubic root of 261904961 is about 639.8054104056.

The spelling of 261904961 in words is "two hundred sixty-one million, nine hundred four thousand, nine hundred sixty-one".