666641261 has 16 divisors (see below), whose sum is σ = 797973120. Its totient is φ = 548857920.

The previous prime is 666641257. The next prime is 666641273. The reversal of 666641261 is 162146666.

It is not a de Polignac number, because 666641261 - 2² = 666641257 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666641221) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 36401 + ... + 51558.

It is an arithmetic number, because the mean of its divisors is an integer number (49873320).

Almost surely, 2^666641261 is an apocalyptic number.

It is an amenable number.

666641261 is a deficient number, since it is larger than the sum of its proper divisors (131331859).

666641261 is a wasteful number, since it uses less digits than its factorization.

666641261 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 88036.

The product of its digits is 62208, while the sum is 38.

The square root of 666641261 is about 25819.3969914094. The cubic root of 666641261 is about 873.5693676483.

The spelling of 666641261 in words is "six hundred sixty-six million, six hundred forty-one thousand, two hundred sixty-one".