666447 has 4 divisors (see below), whose sum is σ = 888600. Its totient is φ = 444296.

The previous prime is 666439. The next prime is 666461. The reversal of 666447 is 744666.

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

It is a cyclic number.

It is not a de Polignac number, because 666447 - 2³ = 666439 is a prime.

It is a D-number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666427) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 111072 + ... + 111077.

It is an arithmetic number, because the mean of its divisors is an integer number (222150).

2⁶⁶⁶⁴⁴⁷ is an apocalyptic number.

666447 is a deficient number, since it is larger than the sum of its proper divisors (222153).

666447 is a wasteful number, since it uses less digits than its factorization.

666447 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 222152.

The product of its digits is 24192, while the sum is 33.

The square root of 666447 is about 816.3620520333. The cubic root of 666447 is about 87.3484505942.

The spelling of 666447 in words is "six hundred sixty-six thousand, four hundred forty-seven".