646332556409 has 2 divisors, whose sum is σ = 646332556410. Its totient is φ = 646332556408.

The previous prime is 646332556403. The next prime is 646332556417. The reversal of 646332556409 is 904655233646.

It is a happy number.

646332556409 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 376992316009 + 269340240400 = 613997^2 + 518980^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-646332556409 is a prime.

It is not a weakly prime, because it can be changed into another prime (646332556403) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 323166278204 + 323166278205.

It is an arithmetic number, because the mean of its divisors is an integer number (323166278205).

Almost surely, 2^646332556409 is an apocalyptic number.

It is an amenable number.

646332556409 is a deficient number, since it is larger than the sum of its proper divisors (1).

646332556409 is an equidigital number, since it uses as much as digits as its factorization.

646332556409 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 13996800, while the sum is 53.

The spelling of 646332556409 in words is "six hundred forty-six billion, three hundred thirty-two million, five hundred fifty-six thousand, four hundred nine".