256280661247 has 4 divisors (see below), whose sum is σ = 275994558280. Its totient is φ = 236566764216.

The previous prime is 256280661223. The next prime is 256280661253. The reversal of 256280661247 is 742166082652.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 256280661247 - 2¹¹ = 256280659199 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 256280661247.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (256280661347) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9856948497 + ... + 9856948522.

It is an arithmetic number, because the mean of its divisors is an integer number (68998639570).

Almost surely, 2^256280661247 is an apocalyptic number.

256280661247 is a deficient number, since it is larger than the sum of its proper divisors (19713897033).

256280661247 is a wasteful number, since it uses less digits than its factorization.

256280661247 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19713897032.

The product of its (nonzero) digits is 1935360, while the sum is 49.

The spelling of 256280661247 in words is "two hundred fifty-six billion, two hundred eighty million, six hundred sixty-one thousand, two hundred forty-seven".