261905311 has 2 divisors, whose sum is σ = 261905312. Its totient is φ = 261905310.

The previous prime is 261905263. The next prime is 261905317. The reversal of 261905311 is 113509162.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 261905311 - 2⁷ = 261905183 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 261905311.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (261905317) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130952655 + 130952656.

It is an arithmetic number, because the mean of its divisors is an integer number (130952656).

Almost surely, 2^261905311 is an apocalyptic number.

261905311 is a deficient number, since it is larger than the sum of its proper divisors (1).

261905311 is an equidigital number, since it uses as much as digits as its factorization.

261905311 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1620, while the sum is 28.

The square root of 261905311 is about 16183.4888389370. The cubic root of 261905311 is about 639.8056954094.

The spelling of 261905311 in words is "two hundred sixty-one million, nine hundred five thousand, three hundred eleven".