646126309 has 2 divisors, whose sum is σ = 646126310. Its totient is φ = 646126308.

The previous prime is 646126307. The next prime is 646126321. The reversal of 646126309 is 903621646.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 417058084 + 229068225 = 20422^2 + 15135^2 .

It is a cyclic number.

It is not a de Polignac number, because 646126309 - 2¹ = 646126307 is a prime.

Together with 646126307, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (646126303) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 323063154 + 323063155.

It is an arithmetic number, because the mean of its divisors is an integer number (323063155).

Almost surely, 2^646126309 is an apocalyptic number.

It is an amenable number.

646126309 is a deficient number, since it is larger than the sum of its proper divisors (1).

646126309 is an equidigital number, since it uses as much as digits as its factorization.

646126309 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 46656, while the sum is 37.

The square root of 646126309 is about 25419.0147133991. The cubic root of 646126309 is about 864.5148845221.

The spelling of 646126309 in words is "six hundred forty-six million, one hundred twenty-six thousand, three hundred nine".