646953409 has 2 divisors, whose sum is σ = 646953410. Its totient is φ = 646953408.

The previous prime is 646953397. The next prime is 646953509. The reversal of 646953409 is 904359646.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 504676225 + 142277184 = 22465^2 + 11928^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-646953409 is a prime.

It is not a weakly prime, because it can be changed into another prime (646953509) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 323476704 + 323476705.

It is an arithmetic number, because the mean of its divisors is an integer number (323476705).

Almost surely, 2^646953409 is an apocalyptic number.

It is an amenable number.

646953409 is a deficient number, since it is larger than the sum of its proper divisors (1).

646953409 is an equidigital number, since it uses as much as digits as its factorization.

646953409 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 699840, while the sum is 46.

The square root of 646953409 is about 25435.2788268578. The cubic root of 646953409 is about 864.8836129283.

The spelling of 646953409 in words is "six hundred forty-six million, nine hundred fifty-three thousand, four hundred nine".