261905011 has 2 divisors, whose sum is σ = 261905012. Its totient is φ = 261905010.

The previous prime is 261904997. The next prime is 261905029. The reversal of 261905011 is 110509162.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 261905011 - 2⁷ = 261904883 is a prime.

It is not a weakly prime, because it can be changed into another prime (261905311) 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, 130952505 + 130952506.

It is an arithmetic number, because the mean of its divisors is an integer number (130952506).

Almost surely, 2^261905011 is an apocalyptic number.

261905011 is a deficient number, since it is larger than the sum of its proper divisors (1).

261905011 is an equidigital number, since it uses as much as digits as its factorization.

261905011 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 540, while the sum is 25.

The square root of 261905011 is about 16183.4795702284. The cubic root of 261905011 is about 639.8054511204.

The spelling of 261905011 in words is "two hundred sixty-one million, nine hundred five thousand, eleven".