66161551011681 has 32 divisors (see below), whose sum is σ = 88940569536000. Its totient is φ = 43745783483520.

The previous prime is 66161551011649. The next prime is 66161551011719. The reversal of 66161551011681 is 18611015516166.

It is not a de Polignac number, because 66161551011681 - 2⁵ = 66161551011649 is a prime.

It is a super-2 number, since 2×66161551011681² (a number of 28 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 66161551011681.

It is not an unprimeable number, because it can be changed into a prime (66161551051681) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (29) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2077335045 + ... + 2077366893.

It is an arithmetic number, because the mean of its divisors is an integer number (2779392798000).

Almost surely, 2^{66161551011681} is an apocalyptic number.

It is an amenable number.

66161551011681 is a deficient number, since it is larger than the sum of its proper divisors (22779018524319).

66161551011681 is a wasteful number, since it uses less digits than its factorization.

66161551011681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 36909.

The product of its (nonzero) digits is 259200, while the sum is 48.

The spelling of 66161551011681 in words is "sixty-six trillion, one hundred sixty-one billion, five hundred fifty-one million, eleven thousand, six hundred eighty-one".