666461 has 2 divisors, whose sum is σ = 666462. Its totient is φ = 666460.

The previous prime is 666439. The next prime is 666467. The reversal of 666461 is 164666.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 511225 + 155236 = 715^2 + 394^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-666461 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (666467) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 333230 + 333231.

It is an arithmetic number, because the mean of its divisors is an integer number (333231).

2⁶⁶⁶⁴⁶¹ is an apocalyptic number.

It is an amenable number.

666461 is a deficient number, since it is larger than the sum of its proper divisors (1).

666461 is an equidigital number, since it uses as much as digits as its factorization.

666461 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5184, while the sum is 29.

The square root of 666461 is about 816.3706266151. The cubic root of 666461 is about 87.3490622306.

It can be divided in two parts, 66 and 6461, that multiplied together give a triangular number (426426 = T₉₂₃).

The spelling of 666461 in words is "six hundred sixty-six thousand, four hundred sixty-one".