256609 has 2 divisors, whose sum is σ = 256610. Its totient is φ = 256608.

The previous prime is 256603. The next prime is 256639. The reversal of 256609 is 906652.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 253009 + 3600 = 503^2 + 60^2 .

It is a cyclic number.

It is not a de Polignac number, because 256609 - 2⁵ = 256577 is a prime.

It is not a weakly prime, because it can be changed into another prime (256603) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128304 + 128305.

It is an arithmetic number, because the mean of its divisors is an integer number (128305).

2²⁵⁶⁶⁰⁹ is an apocalyptic number.

It is an amenable number.

256609 is a deficient number, since it is larger than the sum of its proper divisors (1).

256609 is an equidigital number, since it uses as much as digits as its factorization.

256609 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3240, while the sum is 28.

The square root of 256609 is about 506.5658891003. The cubic root of 256609 is about 63.5463525823.

The spelling of 256609 in words is "two hundred fifty-six thousand, six hundred nine".