668916 has 36 divisors (see below), whose sum is σ = 1791972. Its totient is φ = 209664.

The previous prime is 668903. The next prime is 668929. The reversal of 668916 is 619866.

668916 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (668903) and next prime (668929).

It can be written as a sum of positive squares in 2 ways, for example, as 608400 + 60516 = 780^2 + 246^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is an Ulam number.

It is a congruent number.

It is an unprimeable number.

668916 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 66 + ... + 1158.

It is an arithmetic number, because the mean of its divisors is an integer number (49777).

2⁶⁶⁸⁹¹⁶ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 668916, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (895986).

668916 is an abundant number, since it is smaller than the sum of its proper divisors (1123056).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

668916 is a wasteful number, since it uses less digits than its factorization.

668916 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1120 (or 1115 counting only the distinct ones).

The product of its digits is 15552, while the sum is 36.

The square root of 668916 is about 817.8728507537. The cubic root of 668916 is about 87.4561848662.

668916 divided by its sum of digits (36) gives a palindrome (18581).

The spelling of 668916 in words is "six hundred sixty-eight thousand, nine hundred sixteen".