666261 has 12 divisors (see below), whose sum is σ = 970060. Its totient is φ = 440640.

The previous prime is 666233. The next prime is 666269. The reversal of 666261 is 162666.

It can be written as a sum of positive squares in 2 ways, for example, as 269361 + 396900 = 519^2 + 630^2 .

It is not a de Polignac number, because 666261 - 2⁵ = 666229 is a prime.

It is a Duffinian number.

It is a nialpdrome in base 7.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666269) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1425 + ... + 1833.

2⁶⁶⁶²⁶¹ is an apocalyptic number.

It is an amenable number.

666261 is a deficient number, since it is larger than the sum of its proper divisors (303799).

666261 is a wasteful number, since it uses less digits than its factorization.

666261 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 596 (or 593 counting only the distinct ones).

The product of its digits is 2592, while the sum is 27.

The square root of 666261 is about 816.2481240407. The cubic root of 666261 is about 87.3403237546.

The spelling of 666261 in words is "six hundred sixty-six thousand, two hundred sixty-one".