668861 has 6 divisors (see below), whose sum is σ = 683550. Its totient is φ = 654456.

The previous prime is 668851. The next prime is 668867. The reversal of 668861 is 168866.

It can be written as a sum of positive squares in only one way, i.e., 448900 + 219961 = 670^2 + 469^2 .

It is not a de Polignac number, because 668861 - 2¹⁰ = 667837 is a prime.

It is a Duffinian number.

Its product of digits (13824) is a multiple of the sum of its prime divisors (216).

It is a Curzon 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 668861.

It is not an unprimeable number, because it can be changed into a prime (668867) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 4415 + ... + 4563.

It is an arithmetic number, because the mean of its divisors is an integer number (113925).

2⁶⁶⁸⁸⁶¹ is an apocalyptic number.

It is an amenable number.

668861 is a deficient number, since it is larger than the sum of its proper divisors (14689).

668861 is an equidigital number, since it uses as much as digits as its factorization.

668861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 283 (or 216 counting only the distinct ones).

The product of its digits is 13824, while the sum is 35.

The square root of 668861 is about 817.8392262542. The cubic root of 668861 is about 87.4537878428.

The spelling of 668861 in words is "six hundred sixty-eight thousand, eight hundred sixty-one".