666645 has 24 divisors (see below), whose sum is σ = 1242144. Its totient is φ = 304416.

The previous prime is 666643. The next prime is 666647. The reversal of 666645 is 546666.

It is an interprime number because it is at equal distance from previous prime (666643) and next prime (666647).

It is not a de Polignac number, because 666645 - 2¹ = 666643 is a prime.

It is a Curzon number.

It is a nialpdrome in base 7.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666643) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 282 + ... + 1188.

It is an arithmetic number, because the mean of its divisors is an integer number (51756).

2⁶⁶⁶⁶⁴⁵ is an apocalyptic number.

It is an amenable number.

666645 is a deficient number, since it is larger than the sum of its proper divisors (575499).

666645 is a wasteful number, since it uses less digits than its factorization.

666645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 929 (or 922 counting only the distinct ones).

The product of its digits is 25920, while the sum is 33.

The square root of 666645 is about 816.4833127505. The cubic root of 666645 is about 87.3571000845.

The spelling of 666645 in words is "six hundred sixty-six thousand, six hundred forty-five".