66561801750794 has 32 divisors (see below), whose sum is σ = 120113609719680. Its totient is φ = 27024622693632.

The previous prime is 66561801750709. The next prime is 66561801750811. The reversal of 66561801750794 is 49705710816566.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 66561801750794.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 13365662 + ... + 17656854.

It is an arithmetic number, because the mean of its divisors is an integer number (3753550303740).

Almost surely, 2^{66561801750794} is an apocalyptic number.

66561801750794 is a deficient number, since it is larger than the sum of its proper divisors (53551807968886).

66561801750794 is a wasteful number, since it uses less digits than its factorization.

66561801750794 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4349534.

The product of its (nonzero) digits is 76204800, while the sum is 65.

The spelling of 66561801750794 in words is "sixty-six trillion, five hundred sixty-one billion, eight hundred one million, seven hundred fifty thousand, seven hundred ninety-four".