646404169 has 2 divisors, whose sum is σ = 646404170. Its totient is φ = 646404168.

The previous prime is 646404163. The next prime is 646404203. The reversal of 646404169 is 961404646.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 644499769 + 1904400 = 25387^2 + 1380^2 .

It is a cyclic number.

It is not a de Polignac number, because 646404169 - 2⁹ = 646403657 is a prime.

It is a super-2 number, since 2×646404169² = 835676699401161122, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (646404163) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 323202084 + 323202085.

It is an arithmetic number, because the mean of its divisors is an integer number (323202085).

Almost surely, 2^646404169 is an apocalyptic number.

It is an amenable number.

646404169 is a deficient number, since it is larger than the sum of its proper divisors (1).

646404169 is an equidigital number, since it uses as much as digits as its factorization.

646404169 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 124416, while the sum is 40.

The square root of 646404169 is about 25424.4797193571. The cubic root of 646404169 is about 864.6387920186.

The spelling of 646404169 in words is "six hundred forty-six million, four hundred four thousand, one hundred sixty-nine".