66818081810 has 8 divisors (see below), whose sum is σ = 120272547276. Its totient is φ = 26727232720.

The previous prime is 66818081791. The next prime is 66818081819. The reversal of 66818081810 is 1818081866.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 66558324121 + 259757689 = 257989^2 + 16117^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a super-2 number, since 2×66818081810² (a number of 22 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (66818081819) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3340904081 + ... + 3340904100.

Almost surely, 2^66818081810 is an apocalyptic number.

66818081810 is a deficient number, since it is larger than the sum of its proper divisors (53454465466).

66818081810 is a wasteful number, since it uses less digits than its factorization.

66818081810 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6681808188.

The product of its (nonzero) digits is 147456, while the sum is 47.

The spelling of 66818081810 in words is "sixty-six billion, eight hundred eighteen million, eighty-one thousand, eight hundred ten".