666029909 has 2 divisors, whose sum is σ = 666029910. Its totient is φ = 666029908.

The previous prime is 666029891. The next prime is 666029957. The reversal of 666029909 is 909920666.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 413919025 + 252110884 = 20345^2 + 15878^2 .

It is a cyclic number.

It is not a de Polignac number, because 666029909 - 2²⁴ = 649252693 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 (666029509) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 333014954 + 333014955.

It is an arithmetic number, because the mean of its divisors is an integer number (333014955).

Almost surely, 2^666029909 is an apocalyptic number.

It is an amenable number.

666029909 is a deficient number, since it is larger than the sum of its proper divisors (1).

666029909 is an equidigital number, since it uses as much as digits as its factorization.

666029909 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 314928, while the sum is 47.

The square root of 666029909 is about 25807.5552697267. Note that the first 3 decimals coincide. The cubic root of 666029909 is about 873.3022466095.

The spelling of 666029909 in words is "six hundred sixty-six million, twenty-nine thousand, nine hundred nine".