266188721 has 2 divisors, whose sum is σ = 266188722. Its totient is φ = 266188720.

The previous prime is 266188679. The next prime is 266188751. The reversal of 266188721 is 127881662.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 256800625 + 9388096 = 16025^2 + 3064^2 .

It is a cyclic number.

It is not a de Polignac number, because 266188721 - 2²² = 261994417 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (266188751) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 133094360 + 133094361.

It is an arithmetic number, because the mean of its divisors is an integer number (133094361).

Almost surely, 2^266188721 is an apocalyptic number.

It is an amenable number.

266188721 is a deficient number, since it is larger than the sum of its proper divisors (1).

266188721 is an equidigital number, since it uses as much as digits as its factorization.

266188721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 64512, while the sum is 41.

The square root of 266188721 is about 16315.2910179377. The cubic root of 266188721 is about 643.2748168801.

The spelling of 266188721 in words is "two hundred sixty-six million, one hundred eighty-eight thousand, seven hundred twenty-one".