256006643 has 2 divisors, whose sum is σ = 256006644. Its totient is φ = 256006642.

The previous prime is 256006637. The next prime is 256006651. The reversal of 256006643 is 346600652.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 256006643 - 2¹⁰ = 256005619 is a prime.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (256006243) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128003321 + 128003322.

It is an arithmetic number, because the mean of its divisors is an integer number (128003322).

Almost surely, 2^256006643 is an apocalyptic number.

256006643 is a deficient number, since it is larger than the sum of its proper divisors (1).

256006643 is an equidigital number, since it uses as much as digits as its factorization.

256006643 is an evil number, because the sum of its binary digits is even.

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

The square root of 256006643 is about 16000.2075924033. The cubic root of 256006643 is about 634.9659129821.

The spelling of 256006643 in words is "two hundred fifty-six million, six thousand, six hundred forty-three".