66866681 has 16 divisors (see below), whose sum is σ = 83942400. Its totient is φ = 51934608.

The previous prime is 66866671. The next prime is 66866693. The reversal of 66866681 is 18666866.

It is a cyclic number.

It is not a de Polignac number, because 66866681 - 2²² = 62672377 is a prime.

It is a super-2 number, since 2×66866681² = 8942306055911522, which contains 22 as substring.

It is a Smith number, since the sum of its digits (47) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66866621) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 7871 + ... + 13988.

It is an arithmetic number, because the mean of its divisors is an integer number (5246400).

Almost surely, 2^66866681 is an apocalyptic number.

It is an amenable number.

66866681 is a deficient number, since it is larger than the sum of its proper divisors (17075719).

66866681 is a wasteful number, since it uses less digits than its factorization.

66866681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21908.

The product of its digits is 497664, while the sum is 47.

The square root of 66866681 is about 8177.2049625774. The cubic root of 66866681 is about 405.8852373670.

The spelling of 66866681 in words is "sixty-six million, eight hundred sixty-six thousand, six hundred eighty-one".