256661263 has 2 divisors, whose sum is σ = 256661264. Its totient is φ = 256661262.

The previous prime is 256661227. The next prime is 256661287. The reversal of 256661263 is 362166652.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 256661263 - 2²¹ = 254564111 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (256661213) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128330631 + 128330632.

It is an arithmetic number, because the mean of its divisors is an integer number (128330632).

Almost surely, 2^256661263 is an apocalyptic number.

256661263 is a deficient number, since it is larger than the sum of its proper divisors (1).

256661263 is an equidigital number, since it uses as much as digits as its factorization.

256661263 is an evil number, because the sum of its binary digits is even.

The product of its digits is 77760, while the sum is 37.

The square root of 256661263 is about 16020.6511415735. The cubic root of 256661263 is about 635.5066640547.

The spelling of 256661263 in words is "two hundred fifty-six million, six hundred sixty-one thousand, two hundred sixty-three".