256610661 has 4 divisors (see below), whose sum is σ = 342147552. Its totient is φ = 171073772.

The previous prime is 256610659. The next prime is 256610681. The reversal of 256610661 is 166016652.

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 256610661 - 2¹ = 256610659 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (256610611) 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, 42768441 + ... + 42768446.

It is an arithmetic number, because the mean of its divisors is an integer number (85536888).

Almost surely, 2^256610661 is an apocalyptic number.

It is an amenable number.

256610661 is a deficient number, since it is larger than the sum of its proper divisors (85536891).

256610661 is an equidigital number, since it uses as much as digits as its factorization.

256610661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 85536890.

The product of its (nonzero) digits is 12960, while the sum is 33.

The square root of 256610661 is about 16019.0717895888. The cubic root of 256610661 is about 635.4648969132.

The spelling of 256610661 in words is "two hundred fifty-six million, six hundred ten thousand, six hundred sixty-one".