668545 has 4 divisors (see below), whose sum is σ = 802260. Its totient is φ = 534832.

The previous prime is 668543. The next prime is 668567. The reversal of 668545 is 545866.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 545866 = 2 ⋅272933.

It can be written as a sum of positive squares in 2 ways, for example, as 501264 + 167281 = 708^2 + 409^2 .

It is a cyclic number.

It is not a de Polignac number, because 668545 - 2¹ = 668543 is a prime.

668545 is a lucky number.

It is a self number, because there is not a number n which added to its sum of digits gives 668545.

It is not an unprimeable number, because it can be changed into a prime (668543) 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, 66850 + ... + 66859.

It is an arithmetic number, because the mean of its divisors is an integer number (200565).

2⁶⁶⁸⁵⁴⁵ is an apocalyptic number.

It is an amenable number.

668545 is a deficient number, since it is larger than the sum of its proper divisors (133715).

668545 is a wasteful number, since it uses less digits than its factorization.

668545 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 133714.

The product of its digits is 28800, while the sum is 34.

The square root of 668545 is about 817.6460114255. The cubic root of 668545 is about 87.4400133066.

The spelling of 668545 in words is "six hundred sixty-eight thousand, five hundred forty-five".