266991 has 4 divisors (see below), whose sum is σ = 355992. Its totient is φ = 177992.

The previous prime is 266983. The next prime is 266993. The reversal of 266991 is 199662.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 266991 - 2³ = 266983 is a prime.

It is a D-number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (266993) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 44496 + ... + 44501.

It is an arithmetic number, because the mean of its divisors is an integer number (88998).

2²⁶⁶⁹⁹¹ is an apocalyptic number.

266991 is a deficient number, since it is larger than the sum of its proper divisors (89001).

266991 is an equidigital number, since it uses as much as digits as its factorization.

266991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 89000.

The product of its digits is 5832, while the sum is 33.

The square root of 266991 is about 516.7117184659. The cubic root of 266991 is about 64.3920434340.

The spelling of 266991 in words is "two hundred sixty-six thousand, nine hundred ninety-one".