256381993 has 4 divisors (see below), whose sum is σ = 293008000. Its totient is φ = 219755988.

The previous prime is 256381987. The next prime is 256382003. The reversal of 256381993 is 399183652.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 256381993 - 2⁹ = 256381481 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (256381903) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 18312993 + ... + 18313006.

It is an arithmetic number, because the mean of its divisors is an integer number (73252000).

Almost surely, 2^256381993 is an apocalyptic number.

It is an amenable number.

256381993 is a deficient number, since it is larger than the sum of its proper divisors (36626007).

256381993 is an equidigital number, since it uses as much as digits as its factorization.

256381993 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 36626006.

The product of its digits is 349920, while the sum is 46.

The square root of 256381993 is about 16011.9328314854. The cubic root of 256381993 is about 635.2760847125.

The spelling of 256381993 in words is "two hundred fifty-six million, three hundred eighty-one thousand, nine hundred ninety-three".