256673993 has 4 divisors (see below), whose sum is σ = 257246100. Its totient is φ = 256101888.

The previous prime is 256673987. The next prime is 256673999. The reversal of 256673993 is 399376652.

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

It is an interprime number because it is at equal distance from previous prime (256673987) and next prime (256673999).

It can be written as a sum of positive squares in 2 ways, for example, as 226291849 + 30382144 = 15043^2 + 5512^2 .

It is a cyclic number.

It is not a de Polignac number, because 256673993 - 2⁶ = 256673929 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (256673999) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 285380 + ... + 286277.

It is an arithmetic number, because the mean of its divisors is an integer number (64311525).

Almost surely, 2^256673993 is an apocalyptic number.

It is an amenable number.

256673993 is a deficient number, since it is larger than the sum of its proper divisors (572107).

256673993 is an equidigital number, since it uses as much as digits as its factorization.

256673993 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 572106.

The product of its digits is 1837080, while the sum is 50.

The square root of 256673993 is about 16021.0484363540. The cubic root of 256673993 is about 635.5171705954.

The spelling of 256673993 in words is "two hundred fifty-six million, six hundred seventy-three thousand, nine hundred ninety-three".