666445 has 8 divisors (see below), whose sum is σ = 861336. Its totient is φ = 492096.

The previous prime is 666439. The next prime is 666461. The reversal of 666445 is 544666.

666445 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 4 ways, for example, as 5476 + 660969 = 74^2 + 813^2 .

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 666445 - 2³ = 666437 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5062 + ... + 5191.

It is an arithmetic number, because the mean of its divisors is an integer number (107667).

2⁶⁶⁶⁴⁴⁵ is an apocalyptic number.

666445 is a gapful number since it is divisible by the number (65) formed by its first and last digit.

It is an amenable number.

666445 is a deficient number, since it is larger than the sum of its proper divisors (194891).

666445 is a wasteful number, since it uses less digits than its factorization.

666445 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10271.

The product of its digits is 17280, while the sum is 31.

The square root of 666445 is about 816.3608270857. The cubic root of 666445 is about 87.3483632168.

It can be divided in two parts, 666 and 445, that added together give a palindrome (1111).

The spelling of 666445 in words is "six hundred sixty-six thousand, four hundred forty-five".