666709423 has 2 divisors, whose sum is σ = 666709424. Its totient is φ = 666709422.

The previous prime is 666709399. The next prime is 666709457. The reversal of 666709423 is 324907666.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 666709423 - 2¹⁷ = 666578351 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 666709423.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (666709223) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 333354711 + 333354712.

It is an arithmetic number, because the mean of its divisors is an integer number (333354712).

Almost surely, 2^666709423 is an apocalyptic number.

666709423 is a deficient number, since it is larger than the sum of its proper divisors (1).

666709423 is an equidigital number, since it uses as much as digits as its factorization.

666709423 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 326592, while the sum is 43.

The square root of 666709423 is about 25820.7169342759. The cubic root of 666709423 is about 873.5991398858.

The spelling of 666709423 in words is "six hundred sixty-six million, seven hundred nine thousand, four hundred twenty-three".