646887788669 has 2 divisors, whose sum is σ = 646887788670. Its totient is φ = 646887788668.

The previous prime is 646887788609. The next prime is 646887788683. The reversal of 646887788669 is 966887788646.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 408304386169 + 238583402500 = 638987^2 + 488450^2 .

It is a cyclic number.

It is not a de Polignac number, because 646887788669 - 2²⁴ = 646871011453 is a prime.

It is a super-2 number, since 2×646887788669² (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 (646887788609) 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, 323443894334 + 323443894335.

It is an arithmetic number, because the mean of its divisors is an integer number (323443894335).

Almost surely, 2^646887788669 is an apocalyptic number.

It is an amenable number.

646887788669 is a deficient number, since it is larger than the sum of its proper divisors (1).

646887788669 is an equidigital number, since it uses as much as digits as its factorization.

646887788669 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 9364045824, while the sum is 83.

The spelling of 646887788669 in words is "six hundred forty-six billion, eight hundred eighty-seven million, seven hundred eighty-eight thousand, six hundred sixty-nine".