266135981 has 2 divisors, whose sum is σ = 266135982. Its totient is φ = 266135980.

The previous prime is 266135971. The next prime is 266136001. The reversal of 266135981 is 189531662.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 223233481 + 42902500 = 14941^2 + 6550^2 .

It is a cyclic number.

It is not a de Polignac number, because 266135981 - 2¹⁸ = 265873837 is a prime.

It is a super-2 number, since 2×266135981² = 141656720765664722, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (266135951) 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, 133067990 + 133067991.

It is an arithmetic number, because the mean of its divisors is an integer number (133067991).

Almost surely, 2^266135981 is an apocalyptic number.

It is an amenable number.

266135981 is a deficient number, since it is larger than the sum of its proper divisors (1).

266135981 is an equidigital number, since it uses as much as digits as its factorization.

266135981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 77760, while the sum is 41.

The square root of 266135981 is about 16313.6746626871. The cubic root of 266135981 is about 643.2323300378.

The spelling of 266135981 in words is "two hundred sixty-six million, one hundred thirty-five thousand, nine hundred eighty-one".