256487393 has 2 divisors, whose sum is σ = 256487394. Its totient is φ = 256487392.

The previous prime is 256487369. The next prime is 256487401. The reversal of 256487393 is 393784652.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 238023184 + 18464209 = 15428^2 + 4297^2 .

It is a cyclic number.

It is not a de Polignac number, because 256487393 - 2²² = 252293089 is a prime.

It is not a weakly prime, because it can be changed into another prime (256487333) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128243696 + 128243697.

It is an arithmetic number, because the mean of its divisors is an integer number (128243697).

Almost surely, 2^256487393 is an apocalyptic number.

It is an amenable number.

256487393 is a deficient number, since it is larger than the sum of its proper divisors (1).

256487393 is an equidigital number, since it uses as much as digits as its factorization.

256487393 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1088640, while the sum is 47.

The square root of 256487393 is about 16015.2237886331. The cubic root of 256487393 is about 635.3631279106.

The spelling of 256487393 in words is "two hundred fifty-six million, four hundred eighty-seven thousand, three hundred ninety-three".