66161890928016 has 405 divisors, whose sum is σ = 209689132017729. Its totient is φ = 19463806492416.

The previous prime is 66161890927999. The next prime is 66161890928017. The reversal of 66161890928016 is 61082909816166.

The square root of 66161890928016 is 8133996.

It is a perfect power (a square), and thus also a powerful number.

66161890928016 is a `hidden beast` number, since 6 + 6 + 1 + 618 + 9 + 0 + 9 + 2 + 8 + 0 + 1 + 6 = 666.

It can be written as a sum of positive squares in only one way, i.e., 9787261971600 + 56374628956416 = 3128460^2 + 7508304^2 .

It is a super-2 number, since 2×66161890928016² (a number of 28 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (66161890928017) by changing a digit.

It is a polite number, since it can be written in 80 ways as a sum of consecutive naturals, for example, 29184776515 + ... + 29184778781.

Almost surely, 2^{66161890928016} is an apocalyptic number.

66161890928016 is the 8133996-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 66161890928016

66161890928016 is an abundant number, since it is smaller than the sum of its proper divisors (143527241089713).

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

66161890928016 is a wasteful number, since it uses less digits than its factorization.

66161890928016 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4620 (or 2308 counting only the distinct ones).

The product of its (nonzero) digits is 13436928, while the sum is 63.

The spelling of 66161890928016 in words is "sixty-six trillion, one hundred sixty-one billion, eight hundred ninety million, nine hundred twenty-eight thousand, sixteen".