266161561 has 2 divisors, whose sum is σ = 266161562. Its totient is φ = 266161560.

The previous prime is 266161547. The next prime is 266161573. The reversal of 266161561 is 165161662.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 181171600 + 84989961 = 13460^2 + 9219^2 .

It is a cyclic number.

It is not a de Polignac number, because 266161561 - 2¹¹ = 266159513 is a prime.

It is not a weakly prime, because it can be changed into another prime (266161591) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 133080780 + 133080781.

It is an arithmetic number, because the mean of its divisors is an integer number (133080781).

Almost surely, 2^266161561 is an apocalyptic number.

It is an amenable number.

266161561 is a deficient number, since it is larger than the sum of its proper divisors (1).

266161561 is an equidigital number, since it uses as much as digits as its factorization.

266161561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 12960, while the sum is 34.

The square root of 266161561 is about 16314.4586486956. The cubic root of 266161561 is about 643.2529377434.

The spelling of 266161561 in words is "two hundred sixty-six million, one hundred sixty-one thousand, five hundred sixty-one".