6665078081 has 4 divisors (see below), whose sum is σ = 6666142164. Its totient is φ = 6664014000.

The previous prime is 6665078053. The next prime is 6665078087. The reversal of 6665078081 is 1808705666.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 5156532481 + 1508545600 = 71809^2 + 38840^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-6665078081 is a prime.

It is a super-2 number, since 2×6665078081² = 88846531651653285122, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (6665078087) 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, 522590 + ... + 535191.

It is an arithmetic number, because the mean of its divisors is an integer number (1666535541).

Almost surely, 2^6665078081 is an apocalyptic number.

It is an amenable number.

6665078081 is a deficient number, since it is larger than the sum of its proper divisors (1064083).

6665078081 is a wasteful number, since it uses less digits than its factorization.

6665078081 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1064082.

The product of its (nonzero) digits is 483840, while the sum is 47.

The square root of 6665078081 is about 81639.9294524438. The cubic root of 6665078081 is about 1881.9225542517.

The spelling of 6665078081 in words is "six billion, six hundred sixty-five million, seventy-eight thousand, eighty-one".