256529021 has 4 divisors (see below), whose sum is σ = 293176032. Its totient is φ = 219882012.

The previous prime is 256529011. The next prime is 256529023. The reversal of 256529021 is 120925652.

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 256529021 - 2¹⁴ = 256512637 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (256529023) 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, 18323495 + ... + 18323508.

It is an arithmetic number, because the mean of its divisors is an integer number (73294008).

Almost surely, 2^256529021 is an apocalyptic number.

It is an amenable number.

256529021 is a deficient number, since it is larger than the sum of its proper divisors (36647011).

256529021 is an equidigital number, since it uses as much as digits as its factorization.

256529021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36647010.

The product of its (nonzero) digits is 10800, while the sum is 32.

The square root of 256529021 is about 16016.5233743157. The cubic root of 256529021 is about 635.3974992757.

The spelling of 256529021 in words is "two hundred fifty-six million, five hundred twenty-nine thousand, twenty-one".