261055217 has 2 divisors, whose sum is σ = 261055218. Its totient is φ = 261055216.

The previous prime is 261055181. The next prime is 261055219. The reversal of 261055217 is 712550162.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 241615936 + 19439281 = 15544^2 + 4409^2 .

It is a cyclic number.

It is not a de Polignac number, because 261055217 - 2⁶ = 261055153 is a prime.

Together with 261055219, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 261055217.

It is not a weakly prime, because it can be changed into another prime (261055219) 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 as a sum of consecutive naturals, namely, 130527608 + 130527609.

It is an arithmetic number, because the mean of its divisors is an integer number (130527609).

Almost surely, 2^261055217 is an apocalyptic number.

It is an amenable number.

261055217 is a deficient number, since it is larger than the sum of its proper divisors (1).

261055217 is an equidigital number, since it uses as much as digits as its factorization.

261055217 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4200, while the sum is 29.

The square root of 261055217 is about 16157.2032542764. The cubic root of 261055217 is about 639.1127165825.

The spelling of 261055217 in words is "two hundred sixty-one million, fifty-five thousand, two hundred seventeen".