646634342989 has 2 divisors, whose sum is σ = 646634342990. Its totient is φ = 646634342988.

The previous prime is 646634342969. The next prime is 646634343023. The reversal of 646634342989 is 989243436646.

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., 425701441764 + 220932901225 = 652458^2 + 470035^2 .

It is a cyclic number.

It is not a de Polignac number, because 646634342989 - 2¹⁷ = 646634211917 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 646634342989.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (646634342969) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 323317171494 + 323317171495.

It is an arithmetic number, because the mean of its divisors is an integer number (323317171495).

Almost surely, 2^646634342989 is an apocalyptic number.

It is an amenable number.

646634342989 is a deficient number, since it is larger than the sum of its proper divisors (1).

646634342989 is an equidigital number, since it uses as much as digits as its factorization.

646634342989 is an evil number, because the sum of its binary digits is even.

The product of its digits is 161243136, while the sum is 64.

The spelling of 646634342989 in words is "six hundred forty-six billion, six hundred thirty-four million, three hundred forty-two thousand, nine hundred eighty-nine".