256566665653 has 4 divisors (see below), whose sum is σ = 256748758380. Its totient is φ = 256384572928.

The previous prime is 256566665647. The next prime is 256566665711. The reversal of 256566665653 is 356566665652.

It is a happy number.

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

It can be written as a sum of positive squares in 2 ways, for example, as 33746792209 + 222819873444 = 183703^2 + 472038^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-256566665653 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 256566665591 and 256566665600.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (256566665633) 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, 91044250 + ... + 91047067.

It is an arithmetic number, because the mean of its divisors is an integer number (64187189595).

Almost surely, 2^256566665653 is an apocalyptic number.

It is an amenable number.

256566665653 is a deficient number, since it is larger than the sum of its proper divisors (182092727).

256566665653 is a wasteful number, since it uses less digits than its factorization.

256566665653 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 182092726.

The product of its digits is 174960000, while the sum is 61.

Subtracting 256566665653 from its reverse (356566665652), we obtain a palindrome (99999999999).

The spelling of 256566665653 in words is "two hundred fifty-six billion, five hundred sixty-six million, six hundred sixty-five thousand, six hundred fifty-three".