646609 has 2 divisors, whose sum is σ = 646610. Its totient is φ = 646608.

The previous prime is 646577. The next prime is 646619. The reversal of 646609 is 906646.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 595984 + 50625 = 772^2 + 225^2 .

It is a cyclic number.

It is not a de Polignac number, because 646609 - 2⁵ = 646577 is a prime.

It is not a weakly prime, because it can be changed into another prime (646619) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 323304 + 323305.

It is an arithmetic number, because the mean of its divisors is an integer number (323305).

2⁶⁴⁶⁶⁰⁹ is an apocalyptic number.

It is an amenable number.

646609 is a deficient number, since it is larger than the sum of its proper divisors (1).

646609 is an equidigital number, since it uses as much as digits as its factorization.

646609 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 7776, while the sum is 31.

The square root of 646609 is about 804.1200159180. The cubic root of 646609 is about 86.4730110595.

The spelling of 646609 in words is "six hundred forty-six thousand, six hundred nine".