668861657656 has 16 divisors (see below), whose sum is σ = 1254215813400. Its totient is φ = 334404107424.

The previous prime is 668861657591. The next prime is 668861657657. The reversal of 668861657656 is 656756168866.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (668861657657) 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, 3233595 + ... + 3434218.

Almost surely, 2^668861657656 is an apocalyptic number.

It is an amenable number.

668861657656 is a deficient number, since it is larger than the sum of its proper divisors (585354155744).

668861657656 is a wasteful number, since it uses less digits than its factorization.

668861657656 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6680358 (or 6680354 counting only the distinct ones).

The product of its digits is 522547200, while the sum is 70.

The spelling of 668861657656 in words is "six hundred sixty-eight billion, eight hundred sixty-one million, six hundred fifty-seven thousand, six hundred fifty-six".