256665533 has 4 divisors (see below), whose sum is σ = 267824928. Its totient is φ = 245506140.

The previous prime is 256665503. The next prime is 256665551. The reversal of 256665533 is 335566652.

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 not a de Polignac number, because 256665533 - 2⁶ = 256665469 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (256665503) 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, 5579663 + ... + 5579708.

It is an arithmetic number, because the mean of its divisors is an integer number (66956232).

Almost surely, 2^256665533 is an apocalyptic number.

256665533 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

It is an amenable number.

256665533 is a deficient number, since it is larger than the sum of its proper divisors (11159395).

256665533 is a wasteful number, since it uses less digits than its factorization.

256665533 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11159394.

The product of its digits is 486000, while the sum is 41.

The square root of 256665533 is about 16020.7844065139. The cubic root of 256665533 is about 635.5101882826.

The spelling of 256665533 in words is "two hundred fifty-six million, six hundred sixty-five thousand, five hundred thirty-three".