666408905878081 has 8 divisors (see below), whose sum is σ = 686948452594560. Its totient is φ = 646134385571088.

The previous prime is 666408905878033. The next prime is 666408905878127. The reversal of 666408905878081 is 180878509804666.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 666408905878081 - 2¹¹ = 666408905876033 is a prime.

It is a super-2 number, since 2×666408905878081² (a number of 30 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 666408905877989 and 666408905878007.

It is not an unprimeable number, because it can be changed into a prime (666408905879081) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 66256597266 + ... + 66256607323.

It is an arithmetic number, because the mean of its divisors is an integer number (85868556574320).

Almost surely, 2^{666408905878081} is an apocalyptic number.

It is an amenable number.

666408905878081 is a deficient number, since it is larger than the sum of its proper divisors (20539546716479).

666408905878081 is a wasteful number, since it uses less digits than its factorization.

666408905878081 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 132513204743.

The product of its (nonzero) digits is 1114767360, while the sum is 76.

The spelling of 666408905878081 in words is "six hundred sixty-six trillion, four hundred eight billion, nine hundred five million, eight hundred seventy-eight thousand, eighty-one".