256542643 has 4 divisors (see below), whose sum is σ = 293191600. Its totient is φ = 219893688.

The previous prime is 256542623. The next prime is 256542673. The reversal of 256542643 is 346245652.

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

It is a de Polignac number, because none of the positive numbers 2^k-256542643 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (256542623) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 18324468 + ... + 18324481.

It is an arithmetic number, because the mean of its divisors is an integer number (73297900).

Almost surely, 2^256542643 is an apocalyptic number.

256542643 is a deficient number, since it is larger than the sum of its proper divisors (36648957).

256542643 is an equidigital number, since it uses as much as digits as its factorization.

256542643 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36648956.

The product of its digits is 172800, while the sum is 37.

The square root of 256542643 is about 16016.9486170119. The cubic root of 256542643 is about 635.4087458675.

The spelling of 256542643 in words is "two hundred fifty-six million, five hundred forty-two thousand, six hundred forty-three".