668549 has 4 divisors (see below), whose sum is σ = 764064. Its totient is φ = 573036.

The previous prime is 668543. The next prime is 668567. The reversal of 668549 is 945866.

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 668549 - 2⁴ = 668533 is a prime.

It is a congruent number.

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, 47747 + ... + 47760.

It is an arithmetic number, because the mean of its divisors is an integer number (191016).

2⁶⁶⁸⁵⁴⁹ is an apocalyptic number.

It is an amenable number.

668549 is a deficient number, since it is larger than the sum of its proper divisors (95515).

668549 is an equidigital number, since it uses as much as digits as its factorization.

668549 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 95514.

The product of its digits is 51840, while the sum is 38.

The square root of 668549 is about 817.6484574681. The cubic root of 668549 is about 87.4401876949.

The spelling of 668549 in words is "six hundred sixty-eight thousand, five hundred forty-nine".