666640043 has 2 divisors, whose sum is σ = 666640044. Its totient is φ = 666640042.

The previous prime is 666640031. The next prime is 666640069. The reversal of 666640043 is 340046666.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 666640043 - 2⁶ = 666639979 is a prime.

It is a Sophie Germain prime.

It is a junction number, because it is equal to n+sod(n) for n = 666639985 and 666640012.

It is not a weakly prime, because it can be changed into another prime (666640243) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 333320021 + 333320022.

It is an arithmetic number, because the mean of its divisors is an integer number (333320022).

Almost surely, 2^666640043 is an apocalyptic number.

666640043 is a deficient number, since it is larger than the sum of its proper divisors (1).

666640043 is an equidigital number, since it uses as much as digits as its factorization.

666640043 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 62208, while the sum is 35.

The square root of 666640043 is about 25819.3734044806. The cubic root of 666640043 is about 873.5688356239.

The spelling of 666640043 in words is "six hundred sixty-six million, six hundred forty thousand, forty-three".