256566641 has 4 divisors (see below), whose sum is σ = 259814400. Its totient is φ = 253318884.

The previous prime is 256566637. The next prime is 256566659. The reversal of 256566641 is 146665652.

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 256566641 - 2² = 256566637 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (256566341) 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, 1623761 + ... + 1623918.

It is an arithmetic number, because the mean of its divisors is an integer number (64953600).

Almost surely, 2^256566641 is an apocalyptic number.

It is an amenable number.

256566641 is a deficient number, since it is larger than the sum of its proper divisors (3247759).

256566641 is an equidigital number, since it uses as much as digits as its factorization.

256566641 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3247758.

The product of its digits is 259200, while the sum is 41.

The square root of 256566641 is about 16017.6977434337. The cubic root of 256566641 is about 635.4285581210.

The spelling of 256566641 in words is "two hundred fifty-six million, five hundred sixty-six thousand, six hundred forty-one".