666409157 has 2 divisors, whose sum is σ = 666409158. Its totient is φ = 666409156.

The previous prime is 666409151. The next prime is 666409217. The reversal of 666409157 is 751904666.

It is a happy number.

666409157 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 357739396 + 308669761 = 18914^2 + 17569^2 .

It is a cyclic number.

It is not a de Polignac number, because 666409157 - 2⁸ = 666408901 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (666409151) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 333204578 + 333204579.

It is an arithmetic number, because the mean of its divisors is an integer number (333204579).

Almost surely, 2^666409157 is an apocalyptic number.

It is an amenable number.

666409157 is a deficient number, since it is larger than the sum of its proper divisors (1).

666409157 is an equidigital number, since it uses as much as digits as its factorization.

666409157 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 272160, while the sum is 44.

The square root of 666409157 is about 25814.9018398289. The cubic root of 666409157 is about 873.4679725440.

The spelling of 666409157 in words is "six hundred sixty-six million, four hundred nine thousand, one hundred fifty-seven".