256781641 has 2 divisors, whose sum is σ = 256781642. Its totient is φ = 256781640.

The previous prime is 256781621. The next prime is 256781659. The reversal of 256781641 is 146187652.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 216090000 + 40691641 = 14700^2 + 6379^2 .

It is a cyclic number.

It is not a de Polignac number, because 256781641 - 2¹⁵ = 256748873 is a prime.

It is a super-2 number, since 2×256781641² = 131873622309305762, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 256781594 and 256781603.

It is not a weakly prime, because it can be changed into another prime (256781621) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128390820 + 128390821.

It is an arithmetic number, because the mean of its divisors is an integer number (128390821).

Almost surely, 2^256781641 is an apocalyptic number.

It is an amenable number.

256781641 is a deficient number, since it is larger than the sum of its proper divisors (1).

256781641 is an equidigital number, since it uses as much as digits as its factorization.

256781641 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 80640, while the sum is 40.

The square root of 256781641 is about 16024.4076645597. The cubic root of 256781641 is about 635.6060025932.

The spelling of 256781641 in words is "two hundred fifty-six million, seven hundred eighty-one thousand, six hundred forty-one".