261308779 has 2 divisors, whose sum is σ = 261308780. Its totient is φ = 261308778.

The previous prime is 261308753. The next prime is 261308783. The reversal of 261308779 is 977803162.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 261308779 - 2²⁷ = 127091051 is a prime.

It is not a weakly prime, because it can be changed into another prime (261308279) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130654389 + 130654390.

It is an arithmetic number, because the mean of its divisors is an integer number (130654390).

Almost surely, 2^261308779 is an apocalyptic number.

261308779 is a deficient number, since it is larger than the sum of its proper divisors (1).

261308779 is an equidigital number, since it uses as much as digits as its factorization.

261308779 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 127008, while the sum is 43.

The square root of 261308779 is about 16165.0480667395. The cubic root of 261308779 is about 639.3195722573.

The spelling of 261308779 in words is "two hundred sixty-one million, three hundred eight thousand, seven hundred seventy-nine".