256421243 has 16 divisors (see below), whose sum is σ = 286411776. Its totient is φ = 227970720.

The previous prime is 256421239. The next prime is 256421293. The reversal of 256421243 is 342124652.

It is a cyclic number.

It is not a de Polignac number, because 256421243 - 2² = 256421239 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (256421213) 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 15 ways as a sum of consecutive naturals, for example, 90080 + ... + 92882.

It is an arithmetic number, because the mean of its divisors is an integer number (17900736).

Almost surely, 2^256421243 is an apocalyptic number.

256421243 is a deficient number, since it is larger than the sum of its proper divisors (29990533).

256421243 is a wasteful number, since it uses less digits than its factorization.

256421243 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3074.

The product of its digits is 11520, while the sum is 29.

The square root of 256421243 is about 16013.1584329888. The cubic root of 256421243 is about 635.3085015939.

Adding to 256421243 its reverse (342124652), we get a palindrome (598545895).

The spelling of 256421243 in words is "two hundred fifty-six million, four hundred twenty-one thousand, two hundred forty-three".