256521011 has 2 divisors, whose sum is σ = 256521012. Its totient is φ = 256521010.

The previous prime is 256520951. The next prime is 256521017. The reversal of 256521011 is 110125652.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-256521011 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (256521017) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128260505 + 128260506.

It is an arithmetic number, because the mean of its divisors is an integer number (128260506).

Almost surely, 2^256521011 is an apocalyptic number.

256521011 is a deficient number, since it is larger than the sum of its proper divisors (1).

256521011 is an equidigital number, since it uses as much as digits as its factorization.

256521011 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 600, while the sum is 23.

The square root of 256521011 is about 16016.2733180974. The cubic root of 256521011 is about 635.3908858759.

Adding to 256521011 its reverse (110125652), we get a palindrome (366646663).

The spelling of 256521011 in words is "two hundred fifty-six million, five hundred twenty-one thousand, eleven".