66512021566 has 16 divisors (see below), whose sum is σ = 105029084160. Its totient is φ = 31502663640.

The previous prime is 66512021551. The next prime is 66512021579.

66512021566 is nontrivially palindromic in base 10.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 344355 + ... + 501601.

It is an arithmetic number, because the mean of its divisors is an integer number (6564317760).

Almost surely, 2^66512021566 is an apocalyptic number.

66512021566 is a deficient number, since it is larger than the sum of its proper divisors (38517062594).

66512021566 is a wasteful number, since it uses less digits than its factorization.

66512021566 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 168399.

The product of its (nonzero) digits is 129600, while the sum is 40.

It can be divided in two parts, 665120 and 21566, that added together give a palindrome (686686).

The spelling of 66512021566 in words is "sixty-six billion, five hundred twelve million, twenty-one thousand, five hundred sixty-six".