66810283610821 has 16 divisors (see below), whose sum is σ = 73451525774400. Its totient is φ = 60539520642048.

The previous prime is 66810283610809. The next prime is 66810283610849. The reversal of 66810283610821 is 12801638201866.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 66810283610821 - 2³³ = 66801693676229 is a prime.

It is a super-2 number, since 2×66810283610821² (a number of 28 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66810283610801) 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, 805348060 + ... + 805431013.

It is an arithmetic number, because the mean of its divisors is an integer number (4590720360900).

Almost surely, 2^{66810283610821} is an apocalyptic number.

It is an amenable number.

66810283610821 is a deficient number, since it is larger than the sum of its proper divisors (6641242163579).

66810283610821 is a wasteful number, since it uses less digits than its factorization.

66810283610821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1610779188.

The product of its (nonzero) digits is 1327104, while the sum is 52.

The spelling of 66810283610821 in words is "sixty-six trillion, eight hundred ten billion, two hundred eighty-three million, six hundred ten thousand, eight hundred twenty-one".