256744861 has 2 divisors, whose sum is σ = 256744862. Its totient is φ = 256744860.

The previous prime is 256744849. The next prime is 256744889. The reversal of 256744861 is 168447652.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 148376761 + 108368100 = 12181^2 + 10410^2 .

It is a cyclic number.

It is not a de Polignac number, because 256744861 - 2²³ = 248356253 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (256744261) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128372430 + 128372431.

It is an arithmetic number, because the mean of its divisors is an integer number (128372431).

Almost surely, 2^256744861 is an apocalyptic number.

It is an amenable number.

256744861 is a deficient number, since it is larger than the sum of its proper divisors (1).

256744861 is an equidigital number, since it uses as much as digits as its factorization.

256744861 is an evil number, because the sum of its binary digits is even.

The product of its digits is 322560, while the sum is 43.

The square root of 256744861 is about 16023.2599991388. The cubic root of 256744861 is about 635.5756542332.

The spelling of 256744861 in words is "two hundred fifty-six million, seven hundred forty-four thousand, eight hundred sixty-one".