256781123 has 2 divisors, whose sum is σ = 256781124. Its totient is φ = 256781122.

The previous prime is 256781111. The next prime is 256781137. The reversal of 256781123 is 321187652.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 256781123 - 2⁶ = 256781059 is a prime.

It is a super-2 number, since 2×256781123² = 131873090258282258, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (256781323) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128390561 + 128390562.

It is an arithmetic number, because the mean of its divisors is an integer number (128390562).

Almost surely, 2^256781123 is an apocalyptic number.

256781123 is a deficient number, since it is larger than the sum of its proper divisors (1).

256781123 is an equidigital number, since it uses as much as digits as its factorization.

256781123 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 20160, while the sum is 35.

The square root of 256781123 is about 16024.3915017076. The cubic root of 256781123 is about 635.6055751948.

The spelling of 256781123 in words is "two hundred fifty-six million, seven hundred eighty-one thousand, one hundred twenty-three".