256661523 has 12 divisors (see below), whose sum is σ = 376267528. Its totient is φ = 168553440.

The previous prime is 256661507. The next prime is 256661543. The reversal of 256661523 is 325166652.

It is a happy number.

It is not a de Polignac number, because 256661523 - 2⁴ = 256661507 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (256661543) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 212218 + ... + 213423.

Almost surely, 2^256661523 is an apocalyptic number.

256661523 is a deficient number, since it is larger than the sum of its proper divisors (119606005).

256661523 is a wasteful number, since it uses less digits than its factorization.

256661523 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 425714 (or 425711 counting only the distinct ones).

The product of its digits is 64800, while the sum is 36.

The square root of 256661523 is about 16020.6592560980. The cubic root of 256661523 is about 635.5068786458.

The spelling of 256661523 in words is "two hundred fifty-six million, six hundred sixty-one thousand, five hundred twenty-three".