669891 has 8 divisors (see below), whose sum is σ = 912384. Its totient is φ = 437000.

The previous prime is 669887. The next prime is 669901. The reversal of 669891 is 198966.

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 669891 - 2² = 669887 is a prime.

669891 is a lucky number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 669891.

It is not an unprimeable number, because it can be changed into a prime (669091) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2235 + ... + 2516.

It is an arithmetic number, because the mean of its divisors is an integer number (114048).

2⁶⁶⁹⁸⁹¹ is an apocalyptic number.

669891 is a deficient number, since it is larger than the sum of its proper divisors (242493).

669891 is a wasteful number, since it uses less digits than its factorization.

669891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4801.

The product of its digits is 23328, while the sum is 39.

The square root of 669891 is about 818.4686921318. The cubic root of 669891 is about 87.4986557617.

The spelling of 669891 in words is "six hundred sixty-nine thousand, eight hundred ninety-one".