4001666309 has 2 divisors, whose sum is σ = 4001666310. Its totient is φ = 4001666308.

The previous prime is 4001666303. The next prime is 4001666311. The reversal of 4001666309 is 9036661004.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 2817274084 + 1184392225 = 53078^2 + 34415^2 .

It is a cyclic number.

It is not a de Polignac number, because 4001666309 - 2¹² = 4001662213 is a prime.

Together with 4001666311, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (4001666303) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2000833154 + 2000833155.

It is an arithmetic number, because the mean of its divisors is an integer number (2000833155).

Almost surely, 2^4001666309 is an apocalyptic number.

It is an amenable number.

4001666309 is a deficient number, since it is larger than the sum of its proper divisors (1).

4001666309 is an equidigital number, since it uses as much as digits as its factorization.

4001666309 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 23328, while the sum is 35.

The square root of 4001666309 is about 63258.7251610400. The cubic root of 4001666309 is about 1587.6214464222.

The spelling of 4001666309 in words is "four billion, one million, six hundred sixty-six thousand, three hundred nine".