261646077761617 has 2 divisors, whose sum is σ = 261646077761618. Its totient is φ = 261646077761616.

The previous prime is 261646077761503. The next prime is 261646077761633. The reversal of 261646077761617 is 716167770646162.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 247133208461841 + 14512869299776 = 15720471^2 + 3809576^2 .

It is a cyclic number.

It is not a de Polignac number, because 261646077761617 - 2⁷ = 261646077761489 is a prime.

It is not a weakly prime, because it can be changed into another prime (261646077761317) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130823038880808 + 130823038880809.

It is an arithmetic number, because the mean of its divisors is an integer number (130823038880809).

Almost surely, 2^{261646077761617} is an apocalyptic number.

It is an amenable number.

261646077761617 is a deficient number, since it is larger than the sum of its proper divisors (1).

261646077761617 is an equidigital number, since it uses as much as digits as its factorization.

261646077761617 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 149361408, while the sum is 67.

The spelling of 261646077761617 in words is "two hundred sixty-one trillion, six hundred forty-six billion, seventy-seven million, seven hundred sixty-one thousand, six hundred seventeen".