256501709 has 2 divisors, whose sum is σ = 256501710. Its totient is φ = 256501708.

The previous prime is 256501697. The next prime is 256501717. The reversal of 256501709 is 907105652.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 239568484 + 16933225 = 15478^2 + 4115^2 .

It is a cyclic number.

It is not a de Polignac number, because 256501709 - 2¹² = 256497613 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (256501759) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128250854 + 128250855.

It is an arithmetic number, because the mean of its divisors is an integer number (128250855).

Almost surely, 2^256501709 is an apocalyptic number.

It is an amenable number.

256501709 is a deficient number, since it is larger than the sum of its proper divisors (1).

256501709 is an equidigital number, since it uses as much as digits as its factorization.

256501709 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 18900, while the sum is 35.

The square root of 256501709 is about 16015.6707321298. The cubic root of 256501709 is about 635.3749487506.

The spelling of 256501709 in words is "two hundred fifty-six million, five hundred one thousand, seven hundred nine".