256915493 has 2 divisors, whose sum is σ = 256915494. Its totient is φ = 256915492.

The previous prime is 256915481. The next prime is 256915513. The reversal of 256915493 is 394519652.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 249418849 + 7496644 = 15793^2 + 2738^2 .

It is a cyclic number.

It is not a de Polignac number, because 256915493 - 2²⁶ = 189806629 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (256915403) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128457746 + 128457747.

It is an arithmetic number, because the mean of its divisors is an integer number (128457747).

Almost surely, 2^256915493 is an apocalyptic number.

It is an amenable number.

256915493 is a deficient number, since it is larger than the sum of its proper divisors (1).

256915493 is an equidigital number, since it uses as much as digits as its factorization.

256915493 is an evil number, because the sum of its binary digits is even.

The product of its digits is 291600, while the sum is 44.

The square root of 256915493 is about 16028.5836242632. The cubic root of 256915493 is about 635.7164237224.

The spelling of 256915493 in words is "two hundred fifty-six million, nine hundred fifteen thousand, four hundred ninety-three".