256101809 has 2 divisors, whose sum is σ = 256101810. Its totient is φ = 256101808.

The previous prime is 256101763. The next prime is 256101847. The reversal of 256101809 is 908101652.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 213160000 + 42941809 = 14600^2 + 6553^2 .

It is a cyclic number.

It is not a de Polignac number, because 256101809 - 2⁸ = 256101553 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (256101869) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128050904 + 128050905.

It is an arithmetic number, because the mean of its divisors is an integer number (128050905).

Almost surely, 2^256101809 is an apocalyptic number.

It is an amenable number.

256101809 is a deficient number, since it is larger than the sum of its proper divisors (1).

256101809 is an equidigital number, since it uses as much as digits as its factorization.

256101809 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4320, while the sum is 32.

The square root of 256101809 is about 16003.1812149960. The cubic root of 256101809 is about 635.0445823990.

The spelling of 256101809 in words is "two hundred fifty-six million, one hundred one thousand, eight hundred nine".