51217056666 has 24 divisors (see below), whose sum is σ = 111211023924. Its totient is φ = 17035316160.

The previous prime is 51217056647. The next prime is 51217056679. The reversal of 51217056666 is 66665071215.

It can be written as a sum of positive squares in 2 ways, for example, as 50793890625 + 423166041 = 225375^2 + 20571^2 .

It is a Smith number, since the sum of its digits (45) coincides with the sum of the digits of its prime factors.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3077811 + ... + 3094406.

Almost surely, 2^51217056666 is an apocalyptic number.

51217056666 is an abundant number, since it is smaller than the sum of its proper divisors (59993967258).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

51217056666 is a wasteful number, since it uses less digits than its factorization.

51217056666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6172686 (or 6172683 counting only the distinct ones).

The product of its (nonzero) digits is 453600, while the sum is 45.

The spelling of 51217056666 in words is "fifty-one billion, two hundred seventeen million, fifty-six thousand, six hundred sixty-six".