668819 has 4 divisors (see below), whose sum is σ = 704040. Its totient is φ = 633600.

The previous prime is 668813. The next prime is 668821. The reversal of 668819 is 918866.

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 668819 - 2⁴ = 668803 is a prime.

It is a super-2 number, since 2×668819² = 894637709522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (668813) 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, 17582 + ... + 17619.

It is an arithmetic number, because the mean of its divisors is an integer number (176010).

2⁶⁶⁸⁸¹⁹ is an apocalyptic number.

668819 is a deficient number, since it is larger than the sum of its proper divisors (35221).

668819 is a wasteful number, since it uses less digits than its factorization.

668819 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35220.

The product of its digits is 20736, while the sum is 38.

The square root of 668819 is about 817.8135484326. The cubic root of 668819 is about 87.4519573000.

Subtracting 668819 from its reverse (918866), we obtain a cube (250047 = 63³).

The spelling of 668819 in words is "six hundred sixty-eight thousand, eight hundred nineteen".