646913729909 has 2 divisors, whose sum is σ = 646913729910. Its totient is φ = 646913729908.

The previous prime is 646913729899. The next prime is 646913729927. The reversal of 646913729909 is 909927319646.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 567494035684 + 79419694225 = 753322^2 + 281815^2 .

It is a cyclic number.

It is not a de Polignac number, because 646913729909 - 2⁸ = 646913729653 is a prime.

It is a super-2 number, since 2×646913729909² (a number of 24 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (646913729989) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 323456864954 + 323456864955.

It is an arithmetic number, because the mean of its divisors is an integer number (323456864955).

Almost surely, 2^646913729909 is an apocalyptic number.

It is an amenable number.

646913729909 is a deficient number, since it is larger than the sum of its proper divisors (1).

646913729909 is an equidigital number, since it uses as much as digits as its factorization.

646913729909 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 39680928, while the sum is 65.

The spelling of 646913729909 in words is "six hundred forty-six billion, nine hundred thirteen million, seven hundred twenty-nine thousand, nine hundred nine".