256400663 has 2 divisors, whose sum is σ = 256400664. Its totient is φ = 256400662.

The previous prime is 256400653. The next prime is 256400699. The reversal of 256400663 is 366004652.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 256400663 - 2⁸ = 256400407 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (256400653) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128200331 + 128200332.

It is an arithmetic number, because the mean of its divisors is an integer number (128200332).

Almost surely, 2^256400663 is an apocalyptic number.

256400663 is a deficient number, since it is larger than the sum of its proper divisors (1).

256400663 is an equidigital number, since it uses as much as digits as its factorization.

256400663 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 25920, while the sum is 32.

The square root of 256400663 is about 16012.5158235675. The cubic root of 256400663 is about 635.2915048238.

The spelling of 256400663 in words is "two hundred fifty-six million, four hundred thousand, six hundred sixty-three".