266612561 has 2 divisors, whose sum is σ = 266612562. Its totient is φ = 266612560.

The previous prime is 266612557. The next prime is 266612569. The reversal of 266612561 is 165216662.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 137358400 + 129254161 = 11720^2 + 11369^2 .

It is a cyclic number.

It is not a de Polignac number, because 266612561 - 2² = 266612557 is a prime.

It is not a weakly prime, because it can be changed into another prime (266612569) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 133306280 + 133306281.

It is an arithmetic number, because the mean of its divisors is an integer number (133306281).

Almost surely, 2^266612561 is an apocalyptic number.

It is an amenable number.

266612561 is a deficient number, since it is larger than the sum of its proper divisors (1).

266612561 is an equidigital number, since it uses as much as digits as its factorization.

266612561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 25920, while the sum is 35.

The square root of 266612561 is about 16328.2748935704. The cubic root of 266612561 is about 643.6160547536.

The spelling of 266612561 in words is "two hundred sixty-six million, six hundred twelve thousand, five hundred sixty-one".