266621 has 4 divisors (see below), whose sum is σ = 271200. Its totient is φ = 262044.

The previous prime is 266603. The next prime is 266633. The reversal of 266621 is 126662.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 126662 = 2 ⋅63331.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-266621 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (266641) 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, 2201 + ... + 2318.

It is an arithmetic number, because the mean of its divisors is an integer number (67800).

2²⁶⁶⁶²¹ is an apocalyptic number.

It is an amenable number.

266621 is a deficient number, since it is larger than the sum of its proper divisors (4579).

266621 is an equidigital number, since it uses as much as digits as its factorization.

266621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4578.

The product of its digits is 864, while the sum is 23.

The square root of 266621 is about 516.3535610413. The cubic root of 266621 is about 64.3622845405.

The spelling of 266621 in words is "two hundred sixty-six thousand, six hundred twenty-one".