261601217 has 2 divisors, whose sum is σ = 261601218. Its totient is φ = 261601216.

The previous prime is 261601183. The next prime is 261601231. The reversal of 261601217 is 712106162.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 239661361 + 21939856 = 15481^2 + 4684^2 .

It is a cyclic number.

It is not a de Polignac number, because 261601217 - 2⁸ = 261600961 is a prime.

It is not a weakly prime, because it can be changed into another prime (261601247) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130800608 + 130800609.

It is an arithmetic number, because the mean of its divisors is an integer number (130800609).

Almost surely, 2^261601217 is an apocalyptic number.

It is an amenable number.

261601217 is a deficient number, since it is larger than the sum of its proper divisors (1).

261601217 is an equidigital number, since it uses as much as digits as its factorization.

261601217 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1008, while the sum is 26.

The square root of 261601217 is about 16174.0909172664. The cubic root of 261601217 is about 639.5579768459.

Adding to 261601217 its reverse (712106162), we get a palindrome (973707379).

The spelling of 261601217 in words is "two hundred sixty-one million, six hundred one thousand, two hundred seventeen".