256661501771201 has 2 divisors, whose sum is σ = 256661501771202. Its totient is φ = 256661501771200.

The previous prime is 256661501771153. The next prime is 256661501771267. The reversal of 256661501771201 is 102177105166652.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 255086416530625 + 1575085240576 = 15971425^2 + 1255024^2 .

It is a cyclic number.

It is not a de Polignac number, because 256661501771201 - 2³⁰ = 256660428029377 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 256661501771201.

It is not a weakly prime, because it can be changed into another prime (256661501771281) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128330750885600 + 128330750885601.

It is an arithmetic number, because the mean of its divisors is an integer number (128330750885601).

Almost surely, 2^{256661501771201} is an apocalyptic number.

It is an amenable number.

256661501771201 is a deficient number, since it is larger than the sum of its proper divisors (1).

256661501771201 is an equidigital number, since it uses as much as digits as its factorization.

256661501771201 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1058400, while the sum is 50.

The spelling of 256661501771201 in words is "two hundred fifty-six trillion, six hundred sixty-one billion, five hundred one million, seven hundred seventy-one thousand, two hundred one".