668508773257 has 4 divisors (see below), whose sum is σ = 719932525060. Its totient is φ = 617085021456.

The previous prime is 668508773243. The next prime is 668508773311. The reversal of 668508773257 is 752377805866.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 752377805866 = 2 ⋅376188902933.

It can be written as a sum of positive squares in 2 ways, for example, as 64128471696 + 604380301561 = 253236^2 + 777419^2 .

It is a cyclic number.

It is not a de Polignac number, because 668508773257 - 2²⁷ = 668374555529 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (668508773357) 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, 25711875882 + ... + 25711875907.

It is an arithmetic number, because the mean of its divisors is an integer number (179983131265).

Almost surely, 2^668508773257 is an apocalyptic number.

It is an amenable number.

668508773257 is a deficient number, since it is larger than the sum of its proper divisors (51423751803).

668508773257 is a wasteful number, since it uses less digits than its factorization.

668508773257 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 51423751802.

The product of its (nonzero) digits is 118540800, while the sum is 64.

The spelling of 668508773257 in words is "six hundred sixty-eight billion, five hundred eight million, seven hundred seventy-three thousand, two hundred fifty-seven".