646640404673 has 2 divisors, whose sum is σ = 646640404674. Its totient is φ = 646640404672.

The previous prime is 646640404649. The next prime is 646640404703. The reversal of 646640404673 is 376404046646.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 478349290384 + 168291114289 = 691628^2 + 410233^2 .

It is a cyclic number.

It is not a de Polignac number, because 646640404673 - 2²² = 646636210369 is a prime.

It is a super-2 number, since 2×646640404673² (a number of 24 digits) contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (646640404273) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 323320202336 + 323320202337.

It is an arithmetic number, because the mean of its divisors is an integer number (323320202337).

Almost surely, 2^646640404673 is an apocalyptic number.

It is an amenable number.

646640404673 is a deficient number, since it is larger than the sum of its proper divisors (1).

646640404673 is an equidigital number, since it uses as much as digits as its factorization.

646640404673 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 6967296, while the sum is 50.

The spelling of 646640404673 in words is "six hundred forty-six billion, six hundred forty million, four hundred four thousand, six hundred seventy-three".