660891 has 16 divisors (see below), whose sum is σ = 1099008. Its totient is φ = 343200.

The previous prime is 660887. The next prime is 660893. The reversal of 660891 is 198066.

660891 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 660891 - 2² = 660887 is a prime.

660891 is a modest number, since divided by 891 gives 660 as remainder.

660891 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (660893) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1200 + ... + 1661.

It is an arithmetic number, because the mean of its divisors is an integer number (68688).

2⁶⁶⁰⁸⁹¹ is an apocalyptic number.

660891 is a deficient number, since it is larger than the sum of its proper divisors (438117).

660891 is a wasteful number, since it uses less digits than its factorization.

660891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2882.

The product of its (nonzero) digits is 2592, while the sum is 30.

The square root of 660891 is about 812.9520281050. The cubic root of 660891 is about 87.1050389387.

It can be divided in two parts, 660 and 891, that added together give a palindrome (1551).

The spelling of 660891 in words is "six hundred sixty thousand, eight hundred ninety-one".