266721 has 16 divisors (see below), whose sum is σ = 438144. Its totient is φ = 140544.

The previous prime is 266719. The next prime is 266759. The reversal of 266721 is 127662.

It is a happy number.

It is not a de Polignac number, because 266721 - 2¹ = 266719 is a prime.

It is a super-2 number, since 2×266721² = 142280183682, which contains 22 as substring.

266721 is a lucky number.

It is a junction number, because it is equal to n+sod(n) for n = 266691 and 266700.

It is not an unprimeable number, because it can be changed into a prime (266701) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 216 + ... + 761.

It is an arithmetic number, because the mean of its divisors is an integer number (27384).

2²⁶⁶⁷²¹ is an apocalyptic number.

266721 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

266721 is a deficient number, since it is larger than the sum of its proper divisors (171423).

266721 is a wasteful number, since it uses less digits than its factorization.

266721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1000.

The product of its digits is 1008, while the sum is 24.

The square root of 266721 is about 516.4503848387. The cubic root of 266721 is about 64.3703301982.

The spelling of 266721 in words is "two hundred sixty-six thousand, seven hundred twenty-one".