666042709 has 2 divisors, whose sum is σ = 666042710. Its totient is φ = 666042708.

The previous prime is 666042703. The next prime is 666042721. The reversal of 666042709 is 907240666.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 372605809 + 293436900 = 19303^2 + 17130^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-666042709 is a prime.

It is a super-2 number, since 2×666042709² = 887225780424117362, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (666042703) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 333021354 + 333021355.

It is an arithmetic number, because the mean of its divisors is an integer number (333021355).

Almost surely, 2^666042709 is an apocalyptic number.

It is an amenable number.

666042709 is a deficient number, since it is larger than the sum of its proper divisors (1).

666042709 is an equidigital number, since it uses as much as digits as its factorization.

666042709 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 108864, while the sum is 40.

The square root of 666042709 is about 25807.8032579296. The cubic root of 666042709 is about 873.3078410516.

The spelling of 666042709 in words is "six hundred sixty-six million, forty-two thousand, seven hundred nine".