256531643 has 4 divisors (see below), whose sum is σ = 256568928. Its totient is φ = 256494360.

The previous prime is 256531637. The next prime is 256531663. The reversal of 256531643 is 346135652.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 256531643 - 2⁶ = 256531579 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (256531663) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4988 + ... + 23193.

It is an arithmetic number, because the mean of its divisors is an integer number (64142232).

Almost surely, 2^256531643 is an apocalyptic number.

256531643 is a deficient number, since it is larger than the sum of its proper divisors (37285).

256531643 is an equidigital number, since it uses as much as digits as its factorization.

256531643 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 37284.

The product of its digits is 64800, while the sum is 35.

The square root of 256531643 is about 16016.6052270761. The cubic root of 256531643 is about 635.3996640816.

The spelling of 256531643 in words is "two hundred fifty-six million, five hundred thirty-one thousand, six hundred forty-three".