256661473 has 4 divisors (see below), whose sum is σ = 257568688. Its totient is φ = 255754260.

The previous prime is 256661467. The next prime is 256661497. The reversal of 256661473 is 374166652.

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 a de Polignac number, because none of the positive numbers 2^k-256661473 is a prime.

It is a super-2 number, since 2×256661473² = 131750223445059458, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (256661413) 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, 453183 + ... + 453748.

It is an arithmetic number, because the mean of its divisors is an integer number (64392172).

Almost surely, 2^256661473 is an apocalyptic number.

It is an amenable number.

256661473 is a deficient number, since it is larger than the sum of its proper divisors (907215).

256661473 is an equidigital number, since it uses as much as digits as its factorization.

256661473 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 907214.

The product of its digits is 181440, while the sum is 40.

The square root of 256661473 is about 16020.6576956129. The cubic root of 256661473 is about 635.5068373783.

The spelling of 256661473 in words is "two hundred fifty-six million, six hundred sixty-one thousand, four hundred seventy-three".