261568217 has 2 divisors, whose sum is σ = 261568218. Its totient is φ = 261568216.

The previous prime is 261568199. The next prime is 261568243. The reversal of 261568217 is 712865162.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 221890816 + 39677401 = 14896^2 + 6299^2 .

It is a cyclic number.

It is not a de Polignac number, because 261568217 - 2⁸ = 261567961 is a prime.

It is not a weakly prime, because it can be changed into another prime (261568277) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130784108 + 130784109.

It is an arithmetic number, because the mean of its divisors is an integer number (130784109).

Almost surely, 2^261568217 is an apocalyptic number.

It is an amenable number.

261568217 is a deficient number, since it is larger than the sum of its proper divisors (1).

261568217 is an equidigital number, since it uses as much as digits as its factorization.

261568217 is an evil number, because the sum of its binary digits is even.

The product of its digits is 40320, while the sum is 38.

The square root of 261568217 is about 16173.0707350212. The cubic root of 261568217 is about 639.5310831117.

The spelling of 261568217 in words is "two hundred sixty-one million, five hundred sixty-eight thousand, two hundred seventeen".