266311561 has 2 divisors, whose sum is σ = 266311562. Its totient is φ = 266311560.

The previous prime is 266311531. The next prime is 266311571. The reversal of 266311561 is 165113662.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 247118400 + 19193161 = 15720^2 + 4381^2 .

It is a cyclic number.

It is not a de Polignac number, because 266311561 - 2¹⁷ = 266180489 is a prime.

It is not a weakly prime, because it can be changed into another prime (266311531) 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, 133155780 + 133155781.

It is an arithmetic number, because the mean of its divisors is an integer number (133155781).

Almost surely, 2^266311561 is an apocalyptic number.

It is an amenable number.

266311561 is a deficient number, since it is larger than the sum of its proper divisors (1).

266311561 is an equidigital number, since it uses as much as digits as its factorization.

266311561 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6480, while the sum is 31.

The square root of 266311561 is about 16319.0551503449. The cubic root of 266311561 is about 643.3737538624.

The spelling of 266311561 in words is "two hundred sixty-six million, three hundred eleven thousand, five hundred sixty-one".