666402461 has 2 divisors, whose sum is σ = 666402462. Its totient is φ = 666402460.

The previous prime is 666402419. The next prime is 666402493. The reversal of 666402461 is 164204666.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 556676836 + 109725625 = 23594^2 + 10475^2 .

It is a cyclic number.

It is not a de Polignac number, because 666402461 - 2¹⁸ = 666140317 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (666405461) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 333201230 + 333201231.

It is an arithmetic number, because the mean of its divisors is an integer number (333201231).

Almost surely, 2^666402461 is an apocalyptic number.

It is an amenable number.

666402461 is a deficient number, since it is larger than the sum of its proper divisors (1).

666402461 is an equidigital number, since it uses as much as digits as its factorization.

666402461 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 41472, while the sum is 35.

The square root of 666402461 is about 25814.7721469704. The cubic root of 666402461 is about 873.4650470334.

The spelling of 666402461 in words is "six hundred sixty-six million, four hundred two thousand, four hundred sixty-one".