256781633 has 4 divisors (see below), whose sum is σ = 262245120. Its totient is φ = 251318148.

The previous prime is 256781621. The next prime is 256781641. The reversal of 256781633 is 336187652.

256781633 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 256781633 - 2¹⁰ = 256780609 is a prime.

It is a super-2 number, since 2×256781633² = 131873614092293378, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (256781663) 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, 2731673 + ... + 2731766.

It is an arithmetic number, because the mean of its divisors is an integer number (65561280).

Almost surely, 2^256781633 is an apocalyptic number.

It is an amenable number.

256781633 is a deficient number, since it is larger than the sum of its proper divisors (5463487).

256781633 is an equidigital number, since it uses as much as digits as its factorization.

256781633 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5463486.

The product of its digits is 181440, while the sum is 41.

The square root of 256781633 is about 16024.4074149405. The cubic root of 256781633 is about 635.6059959924.

The spelling of 256781633 in words is "two hundred fifty-six million, seven hundred eighty-one thousand, six hundred thirty-three".