666442081 has 4 divisors (see below), whose sum is σ = 701518000. Its totient is φ = 631366164.

The previous prime is 666442067. The next prime is 666442151. The reversal of 666442081 is 180244666.

666442081 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 666442081 - 2²⁵ = 632887649 is a prime.

It is a super-2 number, since 2×666442081² = 888290094655221122, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 666442081.

It is not an unprimeable number, because it can be changed into a prime (666452081) 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, 17537931 + ... + 17537968.

It is an arithmetic number, because the mean of its divisors is an integer number (175379500).

Almost surely, 2^666442081 is an apocalyptic number.

It is an amenable number.

666442081 is a deficient number, since it is larger than the sum of its proper divisors (35075919).

666442081 is a wasteful number, since it uses less digits than its factorization.

666442081 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35075918.

The product of its (nonzero) digits is 55296, while the sum is 37.

The square root of 666442081 is about 25815.5395256423. The cubic root of 666442081 is about 873.4823568931.

The spelling of 666442081 in words is "six hundred sixty-six million, four hundred forty-two thousand, eighty-one".