256972805 has 18 divisors (see below), whose sum is σ = 315991494. Its totient is φ = 200617296.

The previous prime is 256972801. The next prime is 256972811. The reversal of 256972805 is 508279652.

It can be written as a sum of positive squares in only one way, i.e., 205578244 + 51394561 = 14338^2 + 7169^2 .

It is not a de Polignac number, because 256972805 - 2² = 256972801 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 (256972801) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 2401562 + ... + 2401668.

It is an arithmetic number, because the mean of its divisors is an integer number (17555083).

Almost surely, 2^256972805 is an apocalyptic number.

It is an amenable number.

256972805 is a deficient number, since it is larger than the sum of its proper divisors (59018689).

256972805 is an frugal number, since it uses more digits than its factorization.

256972805 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 353 (or 179 counting only the distinct ones).

The product of its (nonzero) digits is 302400, while the sum is 44.

The square root of 256972805 is about 16030.3713306960. The cubic root of 256972805 is about 635.7636914969.

The spelling of 256972805 in words is "two hundred fifty-six million, nine hundred seventy-two thousand, eight hundred five".